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The Ophiuroidea are marine animals that are closely related to true starfish, or the Asteroidea. Ophiuroids are divided into two groups: brittle-stars and basket-stars.

Brittle-stars generally have five arms joined to a central body disc. Unlike those of true starfish, the central body discs of brittle-stars are usually round and sharply contrast with the arms.

Basket-stars are similar to brittle-stars, but often larger. Unlike the thin snake-like arms of brittle-stars, the arms of basket-stars are often repeatedly branched.