My Derasa seems to have two mantles.... ?

[Project Reef]

Um, I have a large derasa, thick and healthy. (The only clam out of about 15 that survived the dreaded clam infection that has been going on as of late).

Anyhow, When his mantle is fully expanded, underneath his 'main' mantle, is a small mantle lip that seems to be growing out.

I wish I could take a picture..... but this is sort of what it looks like...... (the green representing the "extra" mantle, not quite that large, but you get the idea).

P.S. This is not my clam, just a pic I found on google...

 

[simonh]

I too have a T. deresa which you can see the tissue that appears like a second mantle just protruding over the edge of the shell. It seems perfectly normal and healthy as I have had mine for over a year.