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

Expect Hokkaido sea urchin, boxed like a treasure, and more than 800 wines. —AFAR Media, 2 Sep. 2025

Signature menu dishes include an Oyster tasting menu with fresh native oysters, roasted octopus with marinated bell peppers, olives and basil and spaghetti with sea urchin & green peas. —Joanne Shurvell, Forbes.com, 27 Aug. 2025

With the sharp decline in sea stars, the sea urchins that usually serve as a food source rapidly expanded in population. —Madison E. Goldberg, People.com, 7 Aug. 2025

Previous studies have found symbiotic relationships between squat lobsters and soft or black coral, but only one species has been found to coexist with sea urchins, researchers said. —Irene Wright, Miami Herald, 6 Aug. 2025

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