What do black spots on a red eared sliders shell mean?

ive had my red eared slider 4 bout a year and have no idea how old it is cause it was a gift but yea i kno that once they get to age there shell goes black but idk if this is what it is help please!!!

What do black spots on a red eared sliders shell mean?
One of two things:





Spots that are the same texture and 'level' as the shell are sheer age.





Spots that feel softer, fuzzier, lowered or raised, etc., and especially if they are at ALL 'squishy', it could be a sign of shell rot or fungus.





Try the medical section of http://www.austinsturtlepage.com for ideas to treat rot.



skin rash