What causes black stuff to accumulate on a cat's nose and how can it be safely removed?

The black stuff that accumulates on a cat's nose is usually a combination of dirt, oil, and dried discharge. This can be safely removed by gently wiping the area with a damp cloth or using a pet-safe wipe. It is important to be gentle and avoid using harsh chemicals or pulling on the skin. If the black stuff persists or if there are other symptoms present, it is best to consult a veterinarian for further evaluation and treatment.