For 10 points, name this phylum which includes organisms like sea anemones and jellyfish.
An extinct order in this phylum has a horn-shaped chamber with a wrinkled wall and was called rugosa. One of the largest invertebrates in the world, praya dubia, is within this phylum, which contains such complex colony organisms as siphonophores. Some of its classes include cubozoa, the relatively immobile anthozoa, and scyphozoa. One organism in this phylum causes Irukandji syndrome in humans and another similar one has killed over 60 people in Australia. Bodies of organisms in this phylum consist of mesoglea, and they also possess specialized explosive cells used for prey capture by releasing a toxin. For 10 points, name this phylum which includes organisms like sea anemones and jellyfish.
An extinct order in this phylum has a horn-shaped chamber with a wrinkled wall and was called rugosa.
Cnidaria [or coelenterata]