The Planet Collision Hypothesis suggests that two protoplanets in between Vesisaari and Punainen collided millions of years ago, ejecting material that eventually became Vesisaari’s Moon and Asteroid Ring, as well as Punainen’s two moons.
It is theorized that one of the protoplanets was comprised of many precious metals like iron, nickel, gold, and platinum, which during the collision almost exclusively broke up into asteroids in Vesisaari’s Asteroid Ring. The other protoplanet is believed to have been denser rock, which ended up breaking up into moons.