The fifth day. We're not really making any progress, he thought, in frustration. We need something to show us we're not completely off-course, that we haven't been blinded by a theory.

Footsteps echoing, they made their way down the ramp, past the hangar bay and deeper into the vessel. The steel door to the lab was locked. Johanson tapped in the combination code and the door opened with a soft hiss. He made his way along the bank of switches, aiming on the strip-lights and the desk-lights, flooding the islands of benches and equipment in a cold white glare. The deep-sea simulation chamber hummed in the background.

They climbed on to the walkway and peered through the large oval window. It gave a full view of the inside of the tank. The beam of the internal floodlights picked out small white carapaces and spindly legs scurrying over the artificial seabed. Some of the crabs were moving hesitantly, as though they'd lost their way, scuttling in circles or stopping to consider where they wanted to go. Towards the bottom of the tank, the water obscured the details, but underwater cameras took close-up footage and beamed it on to the monitors at the control desk next to the chamber.

'No real change since yesterday,' said Oliviera.

Johanson scratched his beard. 'We should open some up and see what happens.'

'Crack open some crabs?'

'Why not? We've already established that we can keep them alive in the pressure lab.'

'We've established that we can keep them in a vegetative state,' Oliviera corrected him. 'We don't yet know if they're really alive.'

'The jelly inside them is,' Rubin said thoughtfully, 'but the rest of the crab is no more animate than a car.'

'I agree,' said Oliviera. 'But what's the deal with the jelly? Why isn't it doing anything?'

'What were you expecting it to do?'

'Run around.' Oliviera shrugged. 'Shake its pincers at us. I don't know. Leave the shell, maybe. Those creatures are programmed to march ashore, wreak havoc and die, so this situation puts them in an awkward position. No one's here to give them new orders. They're basically on stand-by.'

'Exactly,' said Johanson, impatiently. 'They're just like battery-operated toys. I agree with Mick. The crab bodies are equipped with just enough nervous tissue to make a dashboard for their drivers. I want to tempt them out of their shells. I want to know what happens if you force them out of their armour in a deep-sea environment.'

'OK.' Oliviera nodded. 'Let's stir things up a bit.'

They left the walkway, clambered down the ladders and walked over to the control desk. The computer enabled them to operate various robots inside the tank. Johanson selected a small, two-piece ROV-unit named Spherobot. A bank of high-resolution screens sprang to life above a console with two joysticks. One showed the inside of the tank. Everything looked elongated and hazy. Spherobot's wide-angle lens was able to survey the whole interior of the tank, but as a result the camera provided a fisheye view.

'How many shall we open?' asked Oliviera.

Johanson's hands flitted over the keyboard, and the angle of the camera shifted upwards by a degree. 'Well, in a good plateful of scampi there's usually at least a dozen.'

ONE OF THE WALLS inside the tank resembled a two-storey garage in which all kinds of deep-sea equipment was stored. Underwater robots of different types and sizes were there, ready to be operated from the control desk. There was no other way to intervene in the artificial world of the chamber.

Johanson activated the controls, and powerful lights flared up on the underside of a robot. Two rotors turned. A box-shaped sled the size of a shopping-trolley floated slowly out of the garage. The top half was packed with machinery, and the rest was made up of an empty basket with fine wire-netting sides. It glided towards the artificial seabed and stopped in front of a small group of motionless crabs. Curved eyeless shells and powerful pincers came into view.

'I'm going to switch to the camera on the globe now,' said Johanson.

The hazy image was replaced by a high-resolution close-up.

Floating above the crabs, the sled released a shiny red ball, no bigger than a football. It was easy to see how the Spherobot had acquired its name. The ball floated into the water, a single cable linking it to the sled, the shiny eye of its camera pointing straight ahead. It brought to mind the flying robot in Star Wars that sparred with Luke Skywalker as he learned to use his light saber. In fact, the Spherobot, with its six miniature thruster pods, was a detailed re-creation of its cinematic predecessor. It travelled a short distance through the water, then sank slowly until it was hovering just above the crabs. They paid no attention to the strange red ball, even when its underside slid open and two slim articulated arms unfolded from inside.

At the end of each arm, an arsenal of equipment began to rotate. Then a robotic grasper protruded from the left arm and a saw from the right. Johanson's hands held both joysticks and shifted carefully forwards, the arms of the robot following each move.

'Hasta la vista, baby,' said Oliviera.

The grasper reached down, grabbed a crab by the middle of its shell and lifted it in front of the camera lens. On the monitor, the creature took on monstrous proportions. Its jaws moved, and its legs kicked, but its pincers dangled limply. Johanson rotated the grasper in a full circle and carefully watched the reaction of the spinning crab.

'Normal motor activity,' he said. 'Its legs are moving fine;

'But it's not responding like a crab,' said Rubin.

'No, it hasn't splayed its pincers or made any obvious show of aggression. It's just a machine.' He moved the second joystick and pressed the button on the top. The circular saw started to rotate and the blade cut into the side of the shell. For an instant the crab's legs twitched wildly.

The shell broke apart.

A milky substance slid out and hovered, trembling, over the debris of the crab.

'Oh, my God,' said Oliviera.

It looked like nothing they'd ever come across. It bore no resemblance to a jellyfish or a squid, but seemed entirely without form. Waves passed through the fringes of the substance, and the creature billowed and flattened. Johanson thought he saw a flash of light shoot out from its centre, but in the harsh glare of the tank it might have been an optical illusion. He was still thinking about it when the creature regrouped into something snake-like and shot away.

Johanson swore, picked up the next crab and cut it open. This time everything happened even faster, and the jelly-like inhabitant of the carapace fled before they had a chance to see it.

'Wow!' Rubin was clearly excited. 'This is crazy! What the hell is this stuff?'

'Something slippery, 'Johanson said, through gritted teeth. 'How the hell are we supposed to stop it getting away?'

'What's the problem? It's got nowhere to go.'

'Well, you try searching the chamber for two shapeless, colourless objects no bigger than a tennis ball!'

'You could open the next one inside the sled basket,' said Oliviera.

'There's no netting at the front. It will get away.'

'No, it won't. The basket closes. You'll just have to be quick.'

Johanson grabbed another crab, spun the Spherobot by 180 degrees and guided it back towards the sled until it was close enough to extend its articulated arms inside the basket. Once they were in, he set the edge of the circular saw against the crab. The shell burst open.

Nothing happened.

'Was it empty?' asked Rubin.

They waited a few seconds, then Johanson guided the spherical robot slowly inside the basket.

'Shit!'

The jelly shot away from the crab, but chose the wrong direction. It hit the back of the basket with a thud. Contracting into a trembling ball, it flitted unsteadily back and forth beside the rear mesh. Its confusion, if that was what it was, lasted only a second.