Twinkle 1, Twinkle 2 and Little Star: Original names for sea stars? We thought so. Commonly referred to as star fish, they are not actually fish, but more closely related to sea urchins and sea cucumbers – that is sure to cause some confusion! The common belief is that sea stars only have 5 arms, but in actual fact, species exist with up to 40 arms! The coolest fact of all is that a sea stars bottom is on its head… Cool.