'Sea fan' definitions:

Definition of 'sea fan'

(from WordNet)
noun
Corals having a treelike or fan-shaped horny skeleton

Definition of 'Sea fan'

From: GCIDE
  • Sea fan \Sea" fan"\ (s[=e]" f[a^]n`). (Zool.) Any gorgonian which branches in a fanlike form, especially Gorgonia flabellum of Florida and the West Indies. [1913 Webster]