Centered in this image is the wheel organ of a Marine Lancelet (Brachiostoma (formerly Amphioxus)). To the left of it is the velum and a portion of the gills and to its right is the inner most portion of the vestibule. The lancelet is a small, translucent, fish-like lower chordate that shows many affinities with the vertebrates. It is thought that vertebrates evolved from ancestors similar to lancelets.