On one of my hermit crabs shell I noticed a red curling tube. It looks like there could be a little black head of some sort protruding from the tube. I have tried to get it with tweezers but never had any luck. The red tube is hard but thin and brittle, like a very thin shell. I broke it with a pair of tweezers a few weeks ago but now it has grown back fully like nothing ever happened!
Any clue on what this is??

Any clue on what this is??




