There are many types of neuron in the brain and they are often classified by shape.
The bipolar neuron has outgrowth on either side of it, often one side has the axon and one side has the dendrite. Sometimes the two sides of the bipolar neuron are both dendrites. Either way the two extensions off the sides of the cell elongate it, making it look....
|Bipolar neuron, Source|
|This is a paper cut-out football used for decorating for superbowl parties|
There are many reasons for the bipolar cell to be ovoid-shaped, and I plan to blog about specific neurons in this category in the future and how their shape matters for what they do. But the real question is, why is the football ovoid-shaped? Why not a sphere like almost every other ball-game?
Well apparently it is because originally (for rugby, which later translated to American football) the ball was a leather-covered pig's bladder.
|inflated pig bladder (source)|
As you can see, the pig bladder is sort of ovoid in shape.
Further refinements on the shape, like the pointed ends and the elongated shape came afterwards, but the oval rather than spherical nature of the original ball is likely based in pig biology.
This rugby and football related information was from here and here.