sea urchin

noun

1. any echinoderm of the class Echinoidea, having a somewhat globular or discoid form, and a shell composed of many calcareous plates covered with projecting spines.
2. a tall evergreen shrub or small tree, Hakea laurina, of Australia, having narrow leaves and dense, globe-shaped clusters of crimson flowers with long yellow stamens.

noun

1. any echinoderm of the class Echinoidea, such as Echinus esculentus (edible sea urchin), typically having a globular body enclosed in a rigid spiny test and occurring in shallow marine waters