Pennatulacea \Pen*nat`u*la"ce*a\, n. pl. [NL. See {Pennatula}.]
(Zool.)
A division of alcyonoid corals, including the seapens and
related kinds. They are able to move about by means of the
hollow muscular peduncle, which also serves to support them
upright in the mud. See {Pennatula}, and Illust. under
{Alcyonaria}.
[1913 Webster]