Multi-scale tracking of the veliger larva of Crepidula sp. (Snail) using Gravity Machine. The larva shows a remarkable spiral sinking trajectory punctuated by periods of linear sinking where the velum (the large, ciliated lobes) are retracted. The spiral sinking is resumed as the larva engages its velum again. Interestingly the radius of the helical path changes continuously and seems to be in active control of the larvae. Note also the mucous thread that the larva is trailing, which is thought to increase drag in the water-column allowing more efficient feeding.