What is this?

I believe that's utricularia gibba. Use a gravel vac next to it when u pull it out. Breaks easy an will spread.

It is green growing concentrated evil.

It is indeed Utricularia gibba. Quite a nuisance, as it will grow, spread and get tangled in everything.

Even leaving a little behind will allow it to grow back (much like Duckweed).

Remove it or you will need fish or shrimp with frickin laser beams attached to their foreheads to get rid of it.

Yay! Thanks for the responses. Now I know I have a pest to combat. Coincidentally I vacuumed out a may fly larva yesterday too. I had no idea it was in my tank, but I saw the bugger swimming in my bucket after a water change. At first I thought it was one of my fry, but nope...legs and antennae. It seems too early in the season for may flies to be getting to my tank.

Again, thanks for the responses

But it's a cool little plant. It's actually carnivorous.

Where do people get this!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I want one! LOL

Breed with it and over time your differences will be resolved.

If you grow it outside in direct sun, it will produce nice looking yellow flowers.