ELI5: Explain Like I'm 5

Spermadhesin

Spermadhesin is a protein that lives inside sperm cells. It helps the sperm cells stick together in clumps so they can swim better and get to where they need to go. Like when you hold hands with your friends to cross the street safely, spermadhesin helps the sperm cells work together as a team to reach their destination. It's like a team captain for the sperm cells!