It's not entirely accurate to say that plant cells are *always* rectangular and animal cells are *always* circular or oval. Here's a more detailed explanation:

Plant cells often appear rectangular due to the presence of a rigid cell wall. This wall, composed of cellulose, provides structural support and gives the cell its defined shape. However, even with the cell wall, plant cells can be various shapes depending on their function and location within the plant.

Animal cells lack a rigid cell wall and rely on their cytoskeleton for shape. The cytoskeleton is a network of protein fibers that provide support and structure. This allows animal cells to be more flexible and can adopt a variety of shapes, including circular, oval, elongated, or irregular.

Here's a table summarizing the key differences:

| Feature | Plant Cell | Animal Cell |

|--------------|-------------------------------------------|------------------------------------------------|

| Shape | Often rectangular, but can vary | Circular, oval, irregular, or elongated |

| Cell Wall | Present | Absent |

| Cytoskeleton | Present, but less prominent than in animals | Present, crucial for maintaining cell shape |

In conclusion: While the presence of a cell wall often gives plant cells a rectangular appearance, both plant and animal cells exhibit diverse shapes depending on their specific functions and environments.