Triploblasts played a crucial role in evolution, precisely because they did have internal organs, and in particular they could ingest food and excrete it. Their excreta became a major resource for other creatures; to get an interestingly complicated world, it is vitally important that shit happens.

T. Pratchett

*Triploblasts - organismi, kuriem embrioģenēzē attīstās 3 šūnu slāņi, no vidējā rodās iekšējie orgāni. Visi dzīvnieki, kas ir sarežģītāki pie medūzām, pieder pie triploblastiem.