This 4mm jellyfish has discovered the secret to immortality. This immortal jellyfish (Turritopsis nutricula) starts life as a benthic polyp (similar to a coral polyp) and will eventually reach the adult medusa stage (shown here). When stressed or starved this tiny jellyfish can regress to its polyp stage and begin life all over again as a genetically identical medusa. Learn more about the immortal jellyfish.