The body is translucent with white pigmentation. Sometimes the body with a yellowish tinge. Just behind the rhinophores there is a triangular white patch.The cerata are translucent white with the pale creamy brown digestive gland. In the adults, the cerata are arranged in six clusters on each side.
Phyllodesmium pecten lives and feeds on octocorals of the family Xeniidae. Its similar to other Xeniidae-feeding Phyllodesmium species.
This nudibranch is a "solar-powered sea slug" (contains zooxanthellae and use the zooxanthellae of their prey).
The name "pecten" refers to radular teeth wirh a comb-like appearance (Lat.pecten = comb).