helianthoidea

from The Century Dictionary.

• An order or some similar group of malacodermatous or soft-bodied anthozoan or zoantharian polyps, of the class Actinozoa; the sea-anemones, in a broad sense, represented by the Actiniidæ and related families. Groups more or less exactly synonymous are Actiniaria, Hexacoralla, and Malacodermata. Also Helianthoida.

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Zoöl.) An order of Anthozoa; the Actinaria.