Just a heads up...
There's a glitch to add level stuff to your pod, DO NOT USE EMITTERS TO MAKE THINGS LAST FOREVER UNLESS YOU MAKE SOMETHING THAT GETS RID OF IT.
I tried blowing up these things, crushing them with fast moving metal blocks, neither worked. I'm stuck with 10 heads piled up in my pod.
Edit: After quitting the game about 5 times, they're gone for some reason.