 "Primary" cilia function as sensory antennae, but are not "undulipodia" as primary cilia do not have the rotary movement mechanism found in motile cilia.Undulipodia are an extension of the cell membrane containing both cytoplasm and a regular arrangement of microtubules known as an axoneme.At the base of the extension lies a structure called the "kinetosome" or "basal body" which is attached via motor proteins to the microtubules.