Corals in the genus Cycloseris are mostly solitary and free living, some attaining 10 centimetres (4 in) in diameter.

The discs are either round or oval and the central mouth, which is surrounded by tentacles, may be a slit.

The polyp sits in a calcareous cup, the corallite, and only extends its tentacles to feed at night.

Cycloseris can be confused with specimens of the related genus Fungia but the former are free living, even as juveniles, while the latter bear a scar showing where they were attached when young.

The genus was reclassified in 2012, to include some species that had previously been classified in the genus Coscinaraea, that are colonial with multiple mouths, in addition to the original species that are free living, with a single central mouth.