Here's why:

* Essential for cell structure and function: Microtubules are essential components of the cytoskeleton, providing structural support and aiding in cell movement, intracellular transport, and cell division.

* Universal across eukaryotes: Both animal and plant cells are eukaryotes, meaning they have a nucleus and other membrane-bound organelles. Microtubules are a fundamental part of the eukaryotic cell structure.

Let me know if you have any other questions about cells!