What is "cycloneritimorpha"

Cycloneritimorpha (nerites and false-limpets) is a clade of land snails, freshwater snails, and sea snails. These are gastropod molluscs within the larger clade Neritimorpha. 14 of the families in the clade are extant, and eight of the families are extinct.

According to the Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), as well as the Cycloneritimorpha, the clade Neritimorpha also contains the (entirely fossil) clade Cyrtoneritimorpha, plus a number of other fossil families that are currently unassigned.

The earliest evolutionary forms of Cycloneritimorpha show double visceral organs, double gills, and normally a double-chambered heart.