How the Hell Did an Island Suddenly Appear, Then Vanish?

It's like a type of floating bog island that grows from piled up downed trees and other biomass and then breaks off from the main land.

Happens on lakes in Wisconsin. See [0] for a very interesting example of what happens when one gets real big and floats away.

[0] https://www.youtube.com/watch?v=X2AG6LAOBYo

Literal definition of "404".