A sperm cell's cargo includes more than a father's DNA. RNA molecules that can contribute to early embryonic development also make the journey. Some of those molecules begin their trip outside the sperm. Researchers have found that tiny protein fibers in semen can help RNA in the surrounding fluid enter sperm cells. In a new study published in Molecular Cell, the team showed that these fibers can bind RNA, enter sperm, and help deliver that cargo to mouse embryos after fertilization.