It seems a bit silly, I admit, but it's a real big threat in this, here, place.

It's an evil little critter that ain't got no heart. [ hence the name. ] I think I been told that them things search fer people to take their hearts. Bit on the creepy side. [ nervous bit of laughter. ] ...and as far as what they look like. Black tar lookin' things with big ol' yell'r eyes.