Suborder Astrocoeiina
  Acroporidae
  Astrocoeniidae
  Pocilloporiidae
Suborder Caryophylliina
  Caryophylliidae
Suborder Dendrophylliina
  Dendrophylliidae
Suborder Faviina
  Faviidae
  Meandrinidae
  Mirulinidae
  Mussidae
  Oculinidae
  Pectiniidae
  Trachyphyllidae
Suborder Fungiina
  Agariciidae
  Fungiidae
  Poritidae
  Siderastreidae
  Thamnasteriidae Scleractinia, also called stony star corals, are exclusively marine animals; they are very similar to sea anemones but generate a hard skeleton. They first appeared in the Middle Triassic and replaced tabulate and rugose corals that went extinct at the end of the Permian.

There are two groups of Scleractinia:

• colonial corals found in clear, shallow tropical waters; they are the world's primary reef-builders.
• solitary corals that are found in all regions of the oceans and that do no build reefs. Some lives in temperate, polar waters, or below the photic zone down to 6000 meters.