Microtubules are tiny, tube-like structures found in the cells of living organisms. They are part of the cell's cytoskeleton, which provides support and shape. Made of proteins called tubulins, microtubules help transport materials within the cell and play a crucial role during cell division by forming the spindle fibers that separate chromosomes. In addition to their structural role, microtubules are involved in various cellular processes, including movement. For example, they are essential for the function of cilia and flagella, which are hair-like structures that help cells like sperm swim or move fluids across epithelial surfaces.