Diamondhead

Petropia is a craggy, geode-like planet where silicon-based beings evolved to build a complex society of separate underground kingdoms. While there are several different gem-based races, from ruby to emerald to sapphire, each with its own distinct abilities and culture, most Petrosapiens now coexist peacefully. After several centuries of warfare, a giant hole was ripped in the sky, revealing a universe far beyond Petropia's heretofore self-contained existence. As its recently enlightened inhabitants have now begun to turn their focus off-world, the rest of the galaxy holds their breath, waiting to find out if these crystalline warriors will wage war or come in peace.
Species: Petrosapien
Petrosapiens are crystalline beings whose bodies are formed entirely out of opaque gemstones and whose rock-hard physiologies make them all virtually invulnerable to physical attack. While jewel-like in appearance, Petrosapiens are no pretty boys. Their diamond-hard bodies make these fearsome warriors incredibly tough. Shards of the razor-sharp crystals jut out at numerous odd angles from their heads and bodies, discouraging physical contact, and also act as powerful weapons that can turn a car into confetti in a matter of seconds. Combined with their increased strength, Petrosapiens' shredding appendages can be especially devastating. Living prisms, Petrosapiens can refract light and beam-based weaponry, channeling them through their bodies and projecting them back at their source. Petrosapiens are particularly vulnerable to sonic vibrations. While a stereo blast might cause them to splinter, certain ultra-high-pitched sound waves can cause them to shatter - and no glue in this galaxy or the next can put a Petrosapien back together again.