juvenile form of animals like molluscs and annelids swimming with a wheel-shaped band of cilia

A trochophore is a type of larva found in marine plankton. It belongs to animals of several related phyla, in the superphylum Lophotrochozoa.

9-hour-old trochophore of the marine gastropod Haliotis asinina
Ontogeny of the Polyplacophora: First image shows the trochophore, second shows the stadium in metamorphosis, third is a juvenile

They have two or more bands of cilia. By moving their cilia rapidly, a water eddy is created. In this way they control the direction of their movement. Also, in this way they bring their food closer, to capture it more easily.