Hopefully I am posting this in the right forum if not could a Admin please move to appropriate forum, but what is this?? It is on the back of a shell of a hermit crab, I got a dozen last week from a LFS and noticed it with I dropped into tank but only today when I noticed the crab either died or abandoned his shell did it "open" up. First time posting from Flickr so hope this link works
http://m.flickr.com/#/photos/97248801@N06/
http://m.flickr.com/#/photos/97248801@N06/