| Edriophus levis Edrioasteroid Bobcaygeon Formation Brechin, Ontario, Canada The most obvious difference between Edrioaster and Edriophus is the direction of the ambulacra. On Edriophus all the amublacra are curved in the clockwise direction. For Edrioaster four amublacra are curves counterclockwise and one is curved clockwise. Size: 3.7 cm diameter | 
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