Sun corals belong to a group of corals known as large-polyp stony corals. This means[clarification needed] that while they produce a hard skeleton, they do not build reefs. Different species have polyps in a variety of colors, including yellow, orange, and shades of black.
Unlike most shallow water corals, Sun corals are not photosynthetic. Tubastraea do not host zooxanthellae, the symbiotic algae that provides energy to the coral via photosynthesis. Instead, they are heterotrophic, and extend long tentacles at night to catch passing zooplankton; their large polyp size allows them to take relatively large zooplankton.
Tubastraea coccinea was first documented in 1943 on Caribbean reefs in Curaçao and Puerto Rico. T. coccinea is an invasive species that was documented to have spread as far north as the Florida Keys National Marine Sanctuary in 2004.
Tubastraea is often found in deep waters because they do not require sunlight for nourishment. They often colonize on artificial surfaces – such as ship wrecks – for this reason.