Urticina crassicornis, the Christmas anemone or rough anemone (family Actiniidae), is a large, colorful sea anemone found in rocky subtidal and intertidal habitats of cold temperate and subarctic waters of the North Pacific and North Atlantic. Its column is covered in adhesive tubercles that trap debris and shell fragments, and its tentacles display striking patterns of red, orange, white, and green coloration. The species is a voracious predator of small fish, crustaceans, and invertebrates and is an important member of subtidal rocky reef communities. Genomic data have been generated for this species and are available in public databases, enabling comparative studies of cnidarian evolution and ecology.