Flat-sided Fire Coral

Found in fairly shallow, high energy surge zones, of coral and rocky reefs.

This hydroid has a powerful sting.

Hydroids look like tiny ferns or feathers, many are smaller than 5cm although some can grow to 50cm.
They are found competing for space with sponges on bare patches of dead coral and rocks.
Stinging hydroid polyps are very small and are carried on the stem and side branches of feather/fern like colonies. The specific layout of the polyps on the branches, as well as the arrangement of the branches are used to classify different species.
The class Hydrozoa encompasses the most diverse group of venomous species and includes the stinging hydroids, hydrocorals (firecorals) and the portugese man of war (siphonophore)
Some species can inflict painful stings.