The plant i get. Its for either eating prey...or protecting itself.
The ice circle is a little strange. The info says it is in the middle of a lake ??
Most likely the Cicle was started by cutting a hole to fish. Then within a few days the weather starts to get warmer and Mother Nature takes over.
I would think it is a FEED lake. Meaning: It is feed by water from one side and drains water off the other side. This creates a current, much like a river only smaller and not as strong. As the lake becomes frozen or covered with ice, the ice is the thinnest in the center or the deepest part. The sun light is able to reach the spot in the center without being blocked, so it will be the first to be thawed. As it thaws, it thaws in a circle. Since the heat source( the sun) is round in shape. You get a circle.
The swirl is created because flowing water is moving in one direction. As it's momentum or flow reaches the thawing circle some of the momentum or flow is redirected around the edge. Once this starts, the water that is flowing underneath feeds the swirl. Like wind blowing into a whirlly'wheel. This redirected flow keeps the circle perfect and round as it thaws.
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No wait...i have a better explanation!!
A alien space ship landed in what they thought was a field...only to realise it was a frozen lake. Then the damn heavy bastard fell THRU. The swirl is from the sinking space ship....YEAH, i like that alot better.