Acoela

thumb|right|Neochildia fusca, a member of Convolutidae (= [[Anaperidae)]]

Acoela, or the acoels, is an order of small and simple invertebrates in the subphylum Acoelomorpha of phylum Xenacoelomorpha, a deep-branching bilaterian group of animals, which resemble flatworms. Historically, they were treated as an order of turbellarian flatworms. About 400 species are known, but probably many more are not yet described.