The sea sponge may seem like an odd choice for genomic research considering that its simple body lacks muscles, organs, and nerve cells, but the creature provides a wealth of information on how multicellular organism arose. When researchers sequenced the sponge’s genome in 2010, they found genes that help individual cells cooperate as a group: how to divide, send signals to one another, and distinguish between friends and outsiders. The sponge genome also contains cancer-related genes, suggesting that individual cells have needed to defend against cancer for as long as they’ve co-existed in the same body.