actinotrocha

from The Century Dictionary.

• noun An embryonic form of a gephyrean worm of the genus Phoronis (which see), which was mistaken for a distinct animal and named Actinotrocha branchiata.
• noun The peculiar larval form of Phoronis, an aberrant genus of marine worms of doubtful affinities, being sometimes classed with the Gephyrea, sometimes with the Molluscoidea, and sometimes with the Hemichordata.

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

• noun plural (Zoöl.) A peculiar larval form of Phoronis, a genus of marine worms, having a circle of ciliated tentacles.