Each ciliated cell has many cilia and microvilli. Microtubules have a major structural role in eukaryotic cilia and flagella. Axonemes are the elongated structures that make up cilia and flagella. The regular beat patterns of eukaryotic cilia and flagella generate motion on a cellular level. The flagella/cilia apparatus pulls the body of the sperm forwards. There may also be protrusions such as microvilli, cilia, bristles, spines and tubercles. Additionally, the microtubules control the beating (movement) of the cilia and flagella. Protozoa are largely defined by their method of locomotion, including flagella, cilia, and pseudopodia. A number of terms related to flagella or cilia are used to characterize eukaryotes. The molecules in the air are detected by enlarged cilia and microvilli. They also make up the internal structure of cilia and flagella. These tubules bear a tuft of cilia or flagellum. Furthermore, it can form specialized structures, such as flagella, cilia, lamellipodia and podosomes. Motile cilia and flagella possess the same 9+2 axoneme structure. These skins are also covered with microvilli between the cilia.