Black scab-like spot on nose

Hi, my cat, Mu, recently developed this small black spot on his nose. At first it looked like a tiny pin prick, which I assumed was from our other kitty while wrestling. However it's increased in size by about 4x in the last month. It feels like a scab, but it doesn't seem to want to heal. I'm wondering if anyone might know what this could be? It also doesn't seem to bother him if I touch it, as well as there's been no sign of infection or swelling.

He's 6 years old and in very good physical health.

Can you have a vet look at it? Make sure to stress that it's growing.