When you pull it up does it have a skunky odor? And or does it have calcium deposits on it? If so it's Chara. I grows 2 to 4 feet thick on thwe bottom of a couple of my ponds. I rake it out occasionally from the trout pond around the edges to keep it from producing shallow water areas that warm too much.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.