These are the whiplike appendages that extend from the surface of many types of eukaryotic cells. If there are many, they're called cilia. If only one, or a few, they are flagella. Flagella also tend to be longer than cilia. Cilia and flagella move liquid past the surface of the cell.

The term Cilia is Latin for eyelashes. The length of a single cilium is 1-10 micrometers and width is less than 1 micrometer. Single-celled eukaryotes, which are organisms with cells that have a nucleus often use cilia to move through liquid.