whats the best kind of sea urchin to get

[Quinn]

http://wetwebmedia.com/urchinsii.htm

It is my understanding that all the species commonly kept in aquariums will eat almost anything. Generally people seem to select a particular species based on size. I had a tuxedo/royal urchin (Mespilia globulus), generally these ones are quite popular as they have very short spines and stay about the size of a tennis ball. One concern related to size is destructiveness. Urchins have a tendency to cruise through anything that gets in their way. They will knock over a coral at some point in time. Do keep tank size, coral concentration in mind.

It has been said that urchins actually contribute to coraline growth by spreading it (or it's spores or whatnot?) around. I didn't have mine long enough to say. More discussion of this here: http://www.google.ca/search?sourceid...pread+coraline

Interestingly, some species are very long lived, up to 200 years!