Endlessly casting about, catching high-class marine creature

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM CORPUS ▪ But please, hold the sea urchin . ▪ Oyster soup with sliced sea urchin is the other original Loiseau signature dish. ▪ Thousands of fertilized sea urchin eggs, starfish and blue clams returned to Earth with the astronauts.

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Sea urchin \Sea" ur"chin\ (Zo["o]l.) Any one of numerous species of echinoderms of the order Echinoidea . Note: When living they are covered with movable spines which are often long and sharp.

Wikipedia Word definitions in Wikipedia
Sea urchins or urchins , archaically called sea hedgehogs , are small, spiny , globular animals that, with their close kin, such as sand dollars , constitute the class Echinoidea of the echinoderm phylum. About 950 species of echinoids inhabit all oceans ...

Wiktionary Word definitions in Wiktionary
n. Any of many marine echinoderms, of the class ''Echinoidea'', commonly found in shallow water, having a complex chewing structure named Aristotle's lantern.

WordNet Word definitions in WordNet
n. shallow-water echinoderms having soft bodies enclosed in thin spiny globular shells