The evolution of mucus: How did we get all this slime?

Mucus Is So Handy That We Evolve It Over And Over Again, Finds Study

Surprising Behavior: Sponges “Sneeze” To Dispose of Waste, Spewing Mucus Into the Sea

Deep-Sea Sponges Can 'Sneeze' Out Mucus, and The Footage Is Weirdly Mesmerizing