Ok, I've got another childhood movie that I can't seem find on the net anywhere.
I don't remember much at all about the plot. I remember there were some sort of large hostile aliens, that (I think) preferred being in tunnels or underground. The biggest hint I can think of was the aliens had some type of energy weapon built into their arm, and it was fueled by copper... I believe. I just remember there was a kid at one point that discovered you could load the alien weapons with a penny. I seem to recall the aliens using long "bricks" of copper usually to fuel the weapons.
Also there was some kind of helpful alien that looked sorta like a ninja. In all black. Don't remember if he had weapons or anything... at least I think he was in this movie, hope I'm not confusing it with something else.
Thanks for any info