Complex sentence: Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish (not to be confused with the rattails), or rabbitfishes.
Split into simpler sentences: Chimaeras are cartilaginous fish in the order Chimaeriformes. They are related to the sharks and rays, and are sometimes called ghost sharks, ratfish (not to be confused with the rattails), or rabbitfishes.