Query: Prehistoric Hexacorallia genera
Relevant documents:
Isastrea
Calamophylliopsis
Columnaria
Comophyllia
Carinthiaphyllum
Mackenzia
Thamnasteria
Pleurodictyum
Heliophyllum
Syringopora
Cerioheterastraea
Gymnophyllum
Coelosimilia
Hexagonaria
Halysites
Rhabdophyllia
Chorisastrea
Conosmilia
Coenites
Diploctenium