Millepora platyphylla

Millepora platyphylla, commonly known as plate fire coral, is a colonial hydrozoan that forms rigid, calcified skeletons despite not being a true stony coral. Colonies typically grow as fused, upright blades or plates with a smooth to slightly nodular surface, colored in shades of cream, tan, or yellow-green. Unlike scleractinian corals, its polyps are tiny and largely retracted into pores in the skeleton, but the colony can deliver a painful sting via nematocysts, giving rise to its common name.

It hosts symbiotic algae (zooxanthellae) that supply photosynthetic energy, and it contributes structurally to reef frameworks, offering habitat and substrate for other reef organisms.

The species occurs widely across the Indo-Pacific, with populations reported from French Polynesia, Papua New Guinea, the Solomon Islands, American Samoa, the Philippines, Madagascar, Micronesia, Australia, Indonesia, Thailand, Vietnam, Yemen, Panama, Taiwan, China, Japan, and Guam. It inhabits shallow marine neritic zones, typically on reef flats, slopes, and lagoons exposed to strong wave action.

Populations are declining due to a combination of pressures: destructive fishing and harvesting practices, outbreaks of coral predators and disease, habitat degradation from coral bleaching and storm damage linked to shifting environmental conditions, and unspecified pollution inputs affecting water quality.

Conservation measures include its presence within numerous marine protected areas across its range, and broader reef monitoring and management programs targeting water quality, fishing regulation, and climate resilience. Species-specific interventions remain limited.

Given ongoing habitat loss and multiple compounding stressors, the species is assessed as Endangered with a decreasing population trend. Its wide distribution offers some buffer against localized extinction, but continued reef degradation suggests further declines are likely without stronger reef protection.