'cup corals' definitions:

Definition of 'cup corals'

From: GCIDE

Cyathophylloid \Cy`a*tho*phyl"loid\, n. (Paleon.) A fossil coral of the family Cyathophyllid[ae]; sometimes extended to fossil corals of other related families belonging to the group Rugosa; -- also called cup corals. Thay are found in paleozoic rocks. [1913 Webster]