In reality, he spends the majority of his time hiding inside a little coconut shell in his crabitat. We check him more-or-less once a day to see if he's alive, and we refresh his water and food. Occasionally we bathe him.
The internet says that crabs need baths. It suggests slightly complicated procedures, but I have a simplified version. I filled a cup of water for him that sits next to his crabitat, at room-temperature. Occasionally one of us grabs Lobster by the shell and dunks him in the water (holding the shell). We'll swish him about for a second or so, then plop him back in the crabitat.
Lobster always comes out of the shell and wiggles around when in the water. The thing is with hermit crabs: you don't have any idea what they're thinking. I always figure he's either thinking, "Oooh, moisture, I'm clean and hydrated, it feels so good!"
Either that or it's something more like, "Oh God ohmigod I can't breathe, what is happening to me, when will it end?!"
I'm kind of hoping it's the first, but really who knows? I could try asking him "wave one claw if you like it, two if you don't", but I'm not sure it would truly answer anything.
Awhile back I decided that maybe he never came out and played because his crabitat was so small. So I made him a corral of sorts, a playpen made of index cards taped together in a circle. I put a mousepad in there, with a nice picture of a beach. Then I added a little toy that my nephew made for him, and a sponge.
When I put Lobster in the corral, it was quite satisfying. He came out and start walking around, exploring the environment. Now that's a more interesting pet -- at least you can see him, and he's doing stuff.
I left him there and went back to work, but we would occasionally glance over and see what he was up to. It was great to see him moving! For a little while I thought the fact that he was walking around meant he was having fun. And it still might mean that, I don't know.... or it might just mean that he's been searching anxiously for his coconut house.
A few times he's shoved his toys up by the side of the wall and climbed on them. Is he playing? Or is he trying to escape??
Irish fears that one day one of us will walk into the lab one morning and hear a crunch underfoot. This is why Daisy always insists that we put him back in the crabitat at night. (An exellent point, by the way, and one with which I always agree.)
But still.... Me, I like to imagine that I'll walk into the lab one day and hear the faint skittering of claws, while Lobster tears past my feet and out the door, perhaps waving a tiny flag and crying in his too-high-for-human-ears voice, "FREEDOM!"