An ice circle is a rare natural phenomenon that occurs in slow moving water in cold climates. Ice circles are thin and circular slabs of ice that rotate slowly in the water. It is believed that they form in eddy currents. In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle.
oh! I bet that’s a bunch of salmon swimming in a big circle (that thawed part).
I don’t know if the fish are there but schools of fish swim in beautiful shapes.
Mullet (I guess mating or spawning) swim in a school as big as a bus (they are small hand-sized fish). I swam right thru it and it didn’t break the formation. The formation was a complicated spiral like a double helix!
So I say fish.