Pencil Urchin
Eucidaris tribuloides
Reef Safe
With Caution
Care Summary
The Pencil Urchin is a distinctive, slow-moving grazer with thick, blunt spines that give it a look unlike any other urchin commonly kept in reef aquariums. It grazes on coralline algae, filamentous algae, and encrusting organisms and is best kept in FOWLR or mixed reef tanks where it has access to natural grazing surfaces. The main issue is coralline grazing, it will systematically clean coralline off rocks in a well-maintained tank, which some hobbyists dislike, so supplement with nori to redirect its attention. Pencil Urchins are hardy and undemanding once acclimated, requiring only stable parameters and open rock surfaces to roam, and they rarely cause problems in tanks large enough to give them space.