Psammechinus microtuberculatus, also known as the green sea urchin,[2][dubious – discuss] in the family Parechinidae.

[3] This is a small, brown, herbivorous[4] sea urchin nearly spherical in shape.

[4] This species occurs in the benthic zone at depths of between 1 and 685 metres.

[4] It prefers to live near sandy areas, and can be found on hard bottoms of mud or rock.

Under hypoxic conditions, it has been observed to discard its "protecting camouflages when confronted with low DO [dissolved oxygen] concentrations" in order "to increase mobility and/or reduce oxygen demand".