
Sounds to me like they are the Brittle Stars pictured on page 434 of Volume 2 of Sprung & Delbeck's The Reef Aquarium. Measuring from the tips of their 5 fully extended arms, they're rarely greater than the diameter of a quarter. Sprung & Delbeck say they "are wonderful complements to the healthy community of a reef aquarium. They sort through the gravel and sand, picking out morsels of detritus as their food." I've had them for years - they reproduce nicely in reef tanks...
if anyone wants them that bad, i just got some LR with 100s of them i can see if i can scratch up a dozen or more depending on what isnt hiding
