Cilium was a short hairlike structure found in abundance on the surface of certain cells.
A cellular fossil discovered near Data's severed head in a cave beneath the Presidio in 2368 was that of the LB10445, a microscopic ciliated lifeform. (TNG: "Time's Arrow")
The superorganism that inhabited Murder Planet in the Hirogen star system was originally identified as a cilium-like vegetation. This vegetation had the ability to fabricate the desires of its intended victims onto its cilium. In 2383, it used its cilia to entangle the nacelles of the USS Protostar then used them to infiltrate the ship's ventral superstructure. (PRO: "Dream Catcher")