The Bubble Coral (Plerogyra sinuosa) is a marine (saltwater) zooxanthellate coral in the Caryophylliidae family of stony corals, although this is not definitive according to some zoologists – they refer to its classification as Incertae sedis or Problematica (which means ‘uncertain placement’ or ‘problematic’). It is in the Cnidaria phylum. It is also known as Grape Coral, Pearl Coral, and Bladder Coral. 

The Bubble Coral ‘bubble’ is grape-sized and roundish. It is cream to yellowish to light beige. Bunched together, like grapes, they form a colony that looks like an inverted cone.