Bornellidae is a family of nudibranch sea slug - marine gastropod molluscs in the superfamily Dendronotoidea.
This family is within the clade Cladobranchia (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).
Nudibranch species within the Bornellidae family have elongated bodies, with pairs of cerata-like dorsal and lateral appendages, with finger-like branches, running along the length of the body. Each of these appendages has an attached cluster of gills. Their rounded head has a tentacle on either side of the mouth, with tiny finger-like papillae. The rhinophores on the head resemble the dorsal appendages.
Nudibranchs within this family are believed to feed exclusively on hydroids.