Ok, you know it's cool:
These oogly little creatures that we'd rather not have as guests actually have lots of guests of their own. They play host to some waste-product-lovin' microbes and the relationship is so efficient that cockroaches have no need for potty breaks. One needs the other as much as the other needs the one. Ahh, symbiosis.
"To survive in hostile environments, cockroaches rely on their own vermin: Blattabacterium, a microbe that hitched a ride inside roaches 140 million years ago, and hasn’t left since.
Researchers who sequenced the Blattabacterium genome have found that it converts waste into molecules necessary for a roach to survive. Every cockroach is a testimony to the power of recycling — thanks to their microbes, they don’t even need to pee."
Wired Science: Cockroach Superpower No. 42: They Don't Need to Pee