What was the creature?

The movie was ok. I wasn't paying 100% attention. I'm ok with movies that don't right away show you the creature. But I like to have a vague idea of what it could be. Was it an alien or plant creature? It had a claw hand. One person mentioned it looked like a big plant then was gone in the beginning. It shot stingers and drooled green goo. What was it? If they clearly told what it was on the radio broadcast I must have missed it.