how do turtle shells grow?

it might just be shedding. if its just clear parts peeling of, its shedding. its part of a turtles life.

P.S. the way to see the sex of a turtle isn't gross. you can tell just by it's shell. :)

No problem. It would be better if the pieces were entire scutes, though. Shells grow the same way as your bones. Most of the shell is vertebrae, ribs, and sternum, plus some dermal bone plates and a keratinous layer (like your nails).

Okay,

Turtle shells grow like this:

When they have scales, new, biggers ones grow right underneath them, so the top ones are not needed anymore. They just pop off. Or I have fun peeling them off my turtles heheh. But this is totally normal!

If there is a clear rims around the shell, that means it is growing. My Red Ear Slider has that:)

You might want to because their shell is part of the bones; its connected to the backbone and the ribs.