The two statements that most likely come from credible sources are:
- There are four classes of jellyfish, and they are known as Scyphozoa, Cubozoa, Hydrozoa, and Staurozoa.
- While jellyfish fossils are rare, the ones that have been found have been dated to over 600 million years BCE.
These statements present factual information that can be verified through scientific literature and research on jellyfish.