Odd "Shell" Found in Mayan Riviera

[Jennifer]

I've never seen a "shell" like this, and I need some help identifying it.

Please and thank you

[paul monfils]

Hi Jennifer,

This is a chiton, a member of a separate class of mollusks, not closely related to either bivalves or gastropods (snail-type mollusks).  Chitons usually live lying flat and firmly attached to rocks or other hard surfaces.  If they get dislodged from the rock surface, they often curl up for protection of their soft undersides.  This one is partially curled up.  There are quite a few species, and I can't tell the exact species from these pictures. The shell of a chiton is made up of a series of narrow curved strips, almost always 8 in number, which are held together by a band of tissue around the outer edge, called the "girdle".

Here are some pictures of live chitons: http://www.snorkelstj.com/chitons.html This page also contains a link to additional information on chitons.