Gastrozoa (lit. "stomach animals") is a clade of Anthostoma.
The Gastrozoa branch evolved around 4021ma. The defining traits of Gastrozoans are their manipulable feeding arms and the development of a stomach, providing higher feeding efficiency compared to Archeanthostoma.
Beyond these developments, the Eugastrozoa branch retains the sessile lifestyle and radially symmetrical body plan of early Anthostomes. However, members of the Tentaclostoma branch have developed mobility and bilateral symmetry.