Glitterball

Quite possibly the most endearing Children's Film Foundation entry, this low-budget charmer sees an alien left behind on a very 1970s Planet Earth, with only two young boys for company.

While this alien comes in the very pocketable form of a little silver ball, it will eat through anything -- which is why local thief Filthy wants to get his grubby hands on it! Wonder if Spielberg ever saw this?