Hi,
Sorry about that I thought you were trying to determine the sex of the turtle.
This sounds like a form of Fungus infection it usually manifest themselves as grey white or black cotton-like layers on slider's shell and skin around the eyes mouth chin legs and anus. dirty water, lack of basking or inadequate feeding or/and in addition to other ailments. Fortunately, if recognized in time, fungal infections are readily curable. The usual therapy consists of salty baths few times a day.
Walter
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