Meep
From KeenWiki
A Meep in Keen 3
The Meep are a jovial race of incredibly bad singers found on the planet Vorticon VI; they are not very bright and exceedingly dangerous, but fortunately easy to kill. They are large, ovoid and green, with short stubby legs and arms. They can produce sound in large booms of several decibels. These are usually lethal to anyone hearing them, and can pass through solid materials without diminishing in strength or lethality, making them even more dangerous. These sound waves are so strong they can even stop Keen's bullets.
Meep are relatively rare, being found in only Valden Park, Fort Vox, Cape Canavorta, and the Castle of the Grand Intellect.
