A few species of jellyfish fertilise eggs internally, and their sperm come with tiny stingers that help them anchor to the tissue within the female gonads Source: https://www.newscientist.com/article/2211369-some-jellyfish-sperm-have-stingers-that-fire-inside-females/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home…