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12 of the most interesting snails in the world

Sea butterfly

Photo: Russ Hopcroft/NOAA

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Sea butterfly

They might not resemble a typical snail, but these elegant sea creatures are among the world's most abundant gastropods. Rather than use its foot to slither along the ground, a sea butterfly's foot has evolved into wing-like lobes, which the animal flaps to propel itself through the ocean. A number of species have lost their shells entirely for more efficient swimming.