Cerata

The tortrix moth genus Cerata is considered a junior synonym of Cydia.
Detail of the aeolid nudibranch Flabellina aff. lineata showing the cerata and cnidosacs.
Drawing of cerata of Fiona pinnata. There are small efferent vessels in cerata with puckered membranous fringe on the inner sides. The vessels are leading to the great median trunk.

Cerata, singular ceras, are anatomical structures found externally in nudibranch sea slugs, especially in aeolid nudibranchs, marine opisthobranch gastropod mollusks in the clade Aeolidida. The word ceras comes from the Greek word "κέρας", meaning "horn", a reference to the shape of these structures.

Cerata are dorsal and lateral outgrowths on the upper surfaces of the body of these nudibranchs.