Divers sometimes report recognising the faces of those missing at sea on the masks that Yagalge carry. Researchers believe this is attributed to pareidolia, as when analysed, the masks are just seabed rocks eroded in ways that appear like faces.
Their poison is strong enough to eat through the hull of a tanker, and they spit it indiscriminately at anything that enters their territory. These Pokémon arose from the spirits of people interred in graves in past ages.