†order Monocyathida Okulitch 1943 (sponge)
Parent taxon: Regulares according to J. J. Sepkoski 2002
Sister taxa: Acanthinocyathida, Ajacicyathida, Capsulocyathida, Clathricyathellus, Pilodicoscinus, Siderocyathus, Tabulacyathida, Tumulocyathellus
Subtaxa: Archaeolynthus, Butakovicyathus, Cryptoporocyathus, Favilynthus, Galinaecyathus, Globosocyathus, Kyarocyathus, Melkanicyathus, Monocyathus, Palaeoconularia, Propriolynthus, Rhabdocyathella, Robertiolynthus, Sajanolynthus, Tegerocyathella, Tumuliolynthus, Tumuloglobosus, Uralocyathella, Veolynthus
Ecology: stationary intermediate-level epifaunal suspension feeder