When eggs of the pseudophyllidean tapeworm Diphyllobothrium latum reach water, an operculum opens to release a free-swimming, spherical, ciliated hexacanth oncosphere known as a coracidium. The coracidium is ingested by the first intermediate host (copepod/Cyclops) and develops into a procercoid.
सूडोफिलाइडियन फीताकृमि Diphyllobothrium latum के अंडे से पानी में निकलने वाले तैरने वाले पक्ष्माभी (ciliated) छह-कांटेदार भ्रूण को कोरासिडियम (Coracidium) कहा जाता है।