Astrangia poculata, the northern star coral (family Rhizangiidae), is a temperate scleractinian coral distributed along the eastern coast of North America from Cape Cod to the Gulf of Mexico. It is facultatively symbiotic with Symbiodiniaceae and can survive both with and without algal symbionts, making it a powerful model for studying the onset and breakdown of coral photosymbiosis. It forms small, encrusting or dome-shaped colonies on hard substrates in shallow to mid-depth waters. It also serves as a model for thermal physiology of temperate corals. Genomic data have been generated for this species and are available in public databases, enabling comparative studies of cnidarian evolution and ecology.