I'm not sure if any of your crabs do this, but it's really weird.
I put a piece of shrimp in the tat for the crabs to eat, and soon after, it was gone. We checked the photographic evidence and saw that Friday had dragged the shrimp into her cocohut! I was worried that it would stink up the tat but it didn't end up smelling. I decided that it seemed Friday really liked the shrimp, so I gave her some more pieces a week or so afterwards. I went to shower, and when I checked about a half-hour later, I peeked into the hut and Friday was sitting in a weird position with her legs wrapped around the piece of shrimp! She'd stolen both pieces!

Similar to the shrimp theft, a piece of cuttlebone had always been available. One night, it disappeared. I shrugged it off and gave them another piece. That one vanished too! My dad convinced me to give them another, and I did. All three ended up in the cocohut! I did a tank remodel today and took the crabs out to mix up all the sand. I found all three pieces of cuttlebone (which had all grown significantly smaller!) and no sign of the shrimp! My crabs are just really weird! :roll:
Two amazing PPs: Jarvis, who has been with me since 7/14/18, and NewCrab (still unnamed) since 1/11/21!
And a tortoiseshell kitty: Delia
I'm still pretty new to this and I'm trying to learn all I can!