Fathom Five National Marine Park, Lake Huron.
Among the more cryptic lake ice formations, ice rosettes are also one of the most common yet poorly explained phenomena. They’re remnants of fractal-like holes with tendrils branching off.
Ice rosettes are loosely theorized to have been drainage holes where, perhaps, water on the surface of the surrounding ice seeped to this low spot and drained beneath the ice into the lake water. There are subtle vertical motions on the lake surface that cause low spots to rise and vice versa. As this happens, the water drains away from the hole and it eventually freezes shut.
Another speculation is that they mark the instance of thermal venting, releasing energy in the water column that melts through the surface from below as it rises. Once the thermal energy is expelled, the vents freeze over, leaving behind a site wound.
Others suggest small gas bubbles from the lake bottom could also play a role. The baffling origins of these puzzling patterns that can be found on any water that freezes is part of their strange and mysterious flare.