West Indian Sea Eggs, Tripneustes Ventricosus. Size will vary from 1 1/2" diameter to about 3" diameter. The urchins body is dark and densely covered with short, white spines. Their "long" tenticales make them a great addition to your tank. They are uncommon to Carribean but we find them occasionly.

These urchins are agressive algae eaters and will quickly eat any algae they can get to. They also have an interesting habit of collecting bits of stuff from the aquarium and carrying it around on their backs.