The facts behind Opabinia.

Opabinia regalis is an extinct stem group marine arthropod found in the Lagerstätte of the Burgess Shale of British Columbia.

Opabinia regalis is an extinct stem group marine arthropod found in the Lagerstätte of the Burgess Shale of British Columbia. Opabinia was a soft-bodied animal, measuring up to 7 cm in body length, and had a segmented trunk with flaps along its sides and a fan-shaped tail. The head showed unusual features: 5 eyes, a mouth under the head and facing backwards, and a clawed proboscis that most likely passed food to its mouth. Opabinia lived on the seafloor, using the proboscis to seek out small, soft food. Fewer than twenty good specimens have been described; 3 specimens of Opabinia are known from the Greater Phyllopod bed, where they constitute less than 0.1% of the community.