The Collaborative International Dictionary
Opelet
Opelet \Ope"let\, n. (Zo["o]l.) A bright-colored European actinian ( Anemonia sulcata, syn. Anthea sulcata); -- so called because it does not retract its tentacles.
Wiktionary
opelet
n. A bright-coloured European actinian (''Anemonia'' or ''Anthea sulcata'').