Description:
Slate pencil urchins are easily identified by their robust, blunted spines.  They reach an adult size of approximately 5 inches in diameter.  The thick spines are attached to a roughly globular test.  Test color ranges from brown to reddish tan.  Spines are typically a dull white color, often tinted with tan or brown banding.  This feature may be obscured by epizoic animals that grow upon the spines and test.  Bases of the spines where muscles attach may be brown to red.  Tube feet are light brown. 

Habitat:
Typical habitats for slate pencil urchins include coral reefs, seagrass beds, especially those of turtlegrass (Thalassia testudinum), rock and shell rubble, hardbottoms, and the quiet waters of back reefs and lagoons.  Pencil urchins are most common at depths below 160 feet, but are collected in waters as deep as 2300 feet.

Range:  
Pencil urchins range from North Carolina south through the Caribbean, Central America, and South America to Brazil.  They are also known from West Africa.