What is a sea urchin benthic plankton or nekton?

Sea urchins are classified as benthic organisms, meaning they live on or near the ocean floor. They are not plankton, which are typically small, drifting organisms in the water column, nor are they nekton, which are actively swimming animals like fish. Sea urchins play an important role in their ecosystem by grazing on algae and contributing to the structure of marine habitats.