‘There!’ pointed Kate. ‘That top window, in that grey house near the church.’

‘They’re probably human, then,’ I said. ‘If they’ve gone inside a house, then they must be.’

‘That’s a load of crap, for a start,’ said Lana. ‘How do you know kriks don’t go inside?’

I didn’t bother answering, but I felt she was being a bit unfair. It’s good to have a theory, even if you can’t prove it and don’t have any evidence for it. That’s called a hypothesis, and scientists like to go on to research things to find out if their hypothesis is true or not. Plus, it would be very nice if kriks couldn’t climb stairs, because going into houses and running upstairs was how I’d always planned to hide from them, if I ever got to land.

‘There!’ shouted Kate again. ‘They’re out.’

Emerging from behind the church, the ten figures appeared on the road, one by one. For a minute we sat, peering at them and hoping, but it was soon obvious they weren’t human. They walked sideways, for a start. And it wasn’t really a walk – more of a scuttle, their curved limbs bent under their shelled bodies and sliding past each other with jerky, artificial bursts of speed.

Kriks.

When they scrambled over rocks or the cliff face, they moved more like large crabs, but on the flat tarmac of the road they were ungainly, their limbs weirdly elongated so they bobbed up and down with exaggerated rhythms as they moved. Most of them still only had four limbs, but a couple – the larger ones – had four extra stumps growing out of their shells. It was their claws that always drew your attention the most: bigger and more powerful than the legs, they were mostly kept low and extended in front of the bodies, but sometimes they were raised, snapping and threatening. Seeing them was one of the few times I felt glad to be on the Jellyfish, and away from the land.

‘Ugh, vile,’ said Lana. ‘I hate those ones with the really wide shells. Yuck.’ She picked up her pen again. ‘Go on and show me what you got for number 15.’

I passed my bit of plastic over to her for her to copy.

‘How are you girls getting on?’ asked Dr Jones.

‘Fine thanks,’ I said. ‘Just checking our answers against each other’s now.’

Dr Jones looked over at Lana’s work suspiciously.

‘How old do you think those ones are?’ I asked.

‘The kriks? Oh, I’d say they’re about two years old.’ Dr Jones squinted over at them. ‘Those ones with the extra limbs are possibly older.’

James came and sat back down next to us.