Call me deranged or call me subversive, just don't call me late for . . . oops, I digress . . . anyway, neither those prickly things not those fan-shaped things have ever ranked among my favorite bivalve groups. I'm kind of partial to Veneridae (Venus Clams), with Cardiidae (Cockles) a close second. I also find Carditidae interesting. The only large shelled molluscs I have ever heard of from the deepest parts of the oceans are bivalves. Some of those thermal vent clams found along the mid-oceanic ridge are a foot long and a couple of pounds apiece. Paul M.