A large semi-spherical or slightly conical shell. Seen from above the melon sea urchin appears to have a pentagonal shape. The interambulacrum plates regularly alternate plates with or without primary tubercles. The spines are short and sparse. When alive the spines are green and the shell is a light green to yellow colour with marked alternating white and brown lines giving the urchin a distinctly segmented appearance.
An algae and small invertebrate consumer. Reproduction most probably take place in the spring (March / April)