A 17-year-old black girl, a new immigrant from Ethiopia to Israel, presented for a routine checkup. Her medical history was unremarkable, and physical examination findings were normal, except for an oval, pigmented lesion measuring 2.0 × 3.5 mm on the bulbar conjunctiva of her left eye. The girl reported having no ocular symptoms (eg, pain, itching, tearing, photophobia) or systemic symptoms. The patient did not remember at what age the eye lesion had appeared, nor whether the lesion had grown in recent years. What diagnosis would you give this patient?