Milleporid Fire corals are tropical, reef-building
hydroids
with hard skeletons and embedded zooxanthellae. They differ from
stony corals in having a smooth surface and tiny pores with thin hairs
that deliver painful stings. Reproduction involves a free-living
medusa stage. Colonies are especially common in shallow water with
good circulation. None occur in Hawaii.
Stylasterid
Hydrocorals are essentially diminutive Fire corals lacking zooxanthellae
that thrive in shaded or very deep waters.
All
coral skeletons illustrated are from scientific collections taken prior
to 1998.
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