What is the outer covering of some eukaryotic cells that provides both flexibility and support?

The outer covering of some eukaryotic cells that provides both flexibility and support is known as a pellicle. This structure is typically found in certain protists, such as euglenoids, where it serves to maintain the cell's shape while allowing for movement and flexibility. The pellicle is often composed of protein layers that can give the cell rigidity without compromising its ability to adapt to varying environments, which is essential for survival in aquatic habitats.

Understanding the role of the pellicle is crucial in examining how these organisms interact with their surroundings and how they move. The structure's flexibility allows cells to change shape as they swim, enhancing their motility. Moreover, by providing a balanced combination of support and flexibility, the pellicle enables cells to withstand physical forces while remaining dynamic and reactive to their environment.