Bo does not know anything about this bowl specifically, but he's reminded of a similar aesthetic being used by certain north German spirit-cults in the late 1700s. These were small cults, practiced in a few villages on the edges of the North Sea, where the population depended on fishing. Every year or so they'd sacrifice someone to the local water spirits by taking a person (ideally some luckless stranger, but one of their own if no one could be found) to a cliff-side at the edge of the ocean, and throwing them off. In exchange, the water-spirits ensured good fishing and no storms. They were mostly wiped out when Napoleon came through, though Bo considers it possible that some could have survived. In particular, they also had the wave-ridges and the swirling whirlpool design, but the eye is an unfamiliar element.