this turtle's about 7 months old, and i don't know what carapace means but it's shell is about 7cm long and wide. i was told it's a boy, and have a female living with it in the same tank, also 7 months with a shell 9cm long and wide and that one has no shell problems becides a little shedding. i'll show a photo of their tank. i first noticed the thing on it's shell about 2 months ago, and he's never acted any differently so i don't think it's something that affects him.
thank for all the help, i appreciate you guys caring for my little guy