naked crab

[bubblegumsweat]

I woke up this morning to my hermit crab being on the side of the glass. He was under the substrate and at first I thought nothing of it because they've dug there before, but when I looked closer he didn't have a shell on. I though he might be molting but don't they molt with their shells on? Also why would he molt on the side were I can see him and light shines through? I didn't see his shell above and none of my hermit crabs have it so I assume he still has it. If he wanted a new shell I have 4 more that would fit him. Should I do something?