Perhaps not “that” rock, but a rock nonetheless.
It sticks out if the water halfway between Poros and Egina in the Saronic gulf. As per Google maps it’s Vrachonisis Petrokarovo… An ancient legend says that small but fierce fish eating dragons live in between the crevices. These live to be a thousand years before they nest and hatch a pair of golden eggs. Or that is what I imagine.
More rocks and cliffs. See buildings for scale.