sea urchin

noun

: any of numerous echinoderms (class Echinoidea) that are usually enclosed in thin brittle globular tests covered with movable spines

Examples of sea urchin in a Sentence

Recent Examples on the Web

Here, beneath the swaying kelp canopy of the Great African Seaforest, a helmet snail rises from the sand, siphon probing like a periscope for the scent of sea urchins. —Tatjana Baleta, Time, 28 May 2026

Among the new species discovered include corals, crabs, shrimps, sea urchins and anemones -- some found living at depths of more than four miles beneath the ocean surface. —Julia Jacobo, ABC News, 19 May 2026

The first courses are elevated seafood appetizers, such as an Otoro bluefin tuna flauta and Hokkaido sea urchin tamal. —Miguel Otárola, Denver Post, 19 May 2026

Ethical Shelling Responsible or ethical shelling is being mindful of only taking empty seashells and always ensuring sand dollars, sea urchins, and other creatures are no longer alive before taking them home. —Gabi De La Rosa, Southern Living, 17 May 2026

Word History

First Known Use

1591, in the meaning defined above

Kids Definition

sea urchin

noun

: any of a class of small marine invertebrate animals that are echinoderms, usually live on or burrow in the sea bottom, and are enclosed in roundish shells covered with spines that can move