Correction: This species is a dorid, not an aeolid. The appendage is a gill plume used for respiration—not a cerata. Unlike other mollusks, these colorful sea slugs don't have shells or gills. | National Geographic

89K views · 634 reactions | The monkey slug caterpillar haunts shade trees and ornamental shrubs like roses and dogwoods across the Eastern U.S. Its fleshy appendages may look a bit like legs, but don’t actually aid in locomotion. Instead, they help the caterpillar disguise itself as a big, hairy spider. More stranger-than-fiction insects from The Caterpillar Lab & Samuel Jaffe: bit.ly/2E0TGRk. | bioGraphic | Facebook