p.s clams do great if they have the proper conditionis, light, calciume, alk, etc. scallops on the other hand have a poor survival rate, in an aquarium mainly cause they need to be fed tons of plankton in order to survice. clams can produce their own food under intense lighting, but should be tried with care. go with a brown specimen such as t. deras, or t. squamosa first, as they are usually more tolerant of light than th emaximas, and croceas. what are you rtank specs? btw
p.p.s. the blue linkia starfish are detritus and micro-flora/faunae eaters. i would only reccommend trying one in a well established system. they are very sensitive to changes in water quality, temp, ph, etc, and must be acclimatised very carefully, they also tend to suffer from shipping and handling, and if you do buy chance purchase one, never touch it with your hands, as it has been reported that the oils on our skins damage teh star, and never expose it to air, as air gets trapped in its water vascular system, causing it to perish.
other than that, good luck
jon