What is round on both sides and has a high in the middle?

I’m black and white, I’m cute but I’ll fight. I roll around with little care, You might want to hug me but you shouldn’t dare.

I roast, I deflate, I deconstruct, yet can elevate. I evince lessons not yet taught. To avoid me, do naught.

You can find me both on your foot and at the end of your fist, but either way, I can be pretty bad for someone’s nose.

I live in darkness, in open air I lose my senses I am flexible, and sometimes offensive I can be known as a mother, and used to take a type of test If I am missing, blaming the cats might be best