Shell rot?

Hopefully Rufina’s pictures came through. Could someone tell me if they think she has shell rot.
Also, at what age is a tortoise considered mature enough to sex and breed?

Thank everyone for all the help I have gotten in the past!

Yes it looks like a little fungus. Get a cheap tube of athletes foot cream and apply it to the area a few days and that should clear it up.

I had some thing similar not too long ago. I bathed them, with a soft tooth brush applied Hibiclens 1:10 ratio with water. Dried and applied cream. I did a 50/50 of athletes foot cream and triple antibiotic cream. With 2-3 days It looked like it never happened. View attachment 281121

Keep Athletes foot cream in your tortoise first aid kit.
If you have Redfoot tortoises, you probably will eventually have to deal with shell fungus.
This photo is from the local Dollar store.
A tube of antibiotic cream for cuts and abrasions. $1
A tube of Athletes foot cream for fungal issues $1
(Actually the antibiotic cream isn't in that shot. But it's the same idea. You don't need to spend a ton)