HCA: Hermit Crab Association

Hello, I have had my crabs for a little over two years, but I only recently discovered this website. It has been a great resource, and now I am hoping someone can help me out a little more!

I recently noticed a strange patch on the lower joint of one of my crab's legs. I wasn't sure what it was, but my research said that illness with hermit crabs is rare, except for sometimes mites, but I don't think this is mites. I was looking closely at him today, though, and I think the patch might be bigger... I could just be paranoid, but I thought maybe someone here could help to identify what this is and whether it is something to worry about?

It's a little hard to see, but it looks like a tiny patch of retained exoskeleton from the last time he molted. It happens sometimes! It should be gone the next time he molts. I wouldn't worry.

Okay. Thanks for your opinion, even with the blurry pictures!