I AM THE KEYMASTER: Sperm Can’t Unlock an Egg Without This Ancient Molecular Key. “They’re the original odd couple: One is massive, spherical and unmoving. The other is tiny, has a tail and never stops swimming. Yet the union of egg and sperm is critical for every sexually reproducing animal on Earth. Exactly how that union occurs has long been a mystery to scientists. A study published Thursday in the journal Cell that relied on Nobel Prize-honored artificial intelligence technology shows that an interlocked bundle of three proteins is the key that lets sperm and egg bind together. That crucial bundle is shared by animals as distantly related as fish and mammals, and most likely including humans.”