Meat-heads.

Found an interesting short film (~7 minutes long) based on the short story "They're Made Out Of Meat" by Terry Bisson. Quite hilarious. And be sure to read the original story as well - it goes into a bit more detail.

They are made out of meat.

EDIT: I should probably also note that it took first place at the First Annual Science Fiction Short Film Festival. (Sidenote: Can you really call something annual if it's only the first year?)