XXL Derasa Clam5" x 3", WYSIWYG and fully conditioned by WWC! Derasa prefer to be placed on a sand bed as they don't readily send out bysal strands to attach themselves to your rock structure. They will also do better if given 4 to 5 hours of brighter daylight spectrum (10 to 14 Kelvin). Smaller individuals will appreciate a shot of fresh phytoplankton a couple times a week and be forewarned, once they start growing they'll suck up your calcium media quicker than