Yeah, I've had a "horn" removed (surgical cutting) & a dozen or so skin cancer spots cryogenically (frozen) removed from my arms ... but, no "barnacles" ... above or below the water line.
* Seborrheic Keratoses or, 'Barnacles of Aging,' are harmless spots and skin growth that occur during adulthood. ... The spots are not cancerous and happen in the outer layer of the person's skin. The main feature of barnacles of aging is their waxy or, 'pasted-on,' appearance.