A cilium (plural cilia)'s an organelle found in eukaryotic cells. Cilia are tail-like projections extending approximately 5–10 micrometers from the cell body. There're two types of cilia: motile cilia and non-motile, or primary, cilia, which typically serve as sensory organelles. Along with flagella, they make up a group of organelles known as undulipodia. Primary cilia may be "viewed as sensory cellular antennae that coordinate a large number of cellular signaling pathways, sometimes cou… (More on Cilium)