Green sea urchins can be found both the Atlantic and Pacific Oceans. In the Pacific Ocean, they are found from northern Washington State to Alaska, and in the Atlantic Ocean from New Jersey to the Arctic. Green urchins live in rocky substratum of the intertidal zone at depths of 10 m; although they can be found down to 1,200 meters.  They move by using their spines and hundreds of miniature tube 'feet' located under their body, which have tiny suction cups to grip surfaces.

Green sea urchin are the shape of a slightly flattened globe and are covered in short, sharp, movable spines. This species can be pale green, or greenish tinged with purple or brown on their spines. Their mouth is located on the underside of the body and they feed by scraping fine algae off of hard substrate with their teeth. Green sea urchins are generally harvested for their gonads, which are known as "uni" in sushi restaraunts.