You might look a little differently at the next lobster you see when you learn how they excrete their waste. Good thing we don't eat their faces, right? A lobster pees from openings (nephrophores) located at the base of its second antennae. These excretory organs are called green glands and include a sac linked to a bladder by a coiled tube [source: Lobster Conservancy].
Lobsters also excrete from other places on their bodies, including their gills and digestive glands. Excreting from the nephrophores isn't just about getting rid of toxic waste products, though -- it's part of the lobster mating ritual.
Male lobsters love to fight. Female lobsters seek out the most aggressive, dominant male in the area and show their interest by peeing repeatedly into his shelter. Their urine contains pheromones, which calm him down and get him in the mood, so to speak. Lobsters also urinate in each others' faces during fights to express themselves [source: Markey].