J is for Jellyfish.
Back in the Cambrian, 700 million years ago, before there were even plants, back when the only things around were trilobites and anomalocarises, there were jellyfish. All the arthropods were like, "You jellyfish are never going to make it, ha-ha, with your soft bodies. Good luck." But it turns out the jellyfish outlived them all. Way to go, jellyfish.
When a mommy and daddy jellyfish love each other very, very much, the daddy releases sperm into the mommy's mouth, which is not considered kinky if you're a jellyfish, and pretty soon there are a bunch of baby polyps anchored to the ocean floor, their tentacles waving upward like adorable baby birds, only not so adorable and capable of stinging. Several polyps may share a single stomach, and yet they never complain, unlike human offspring who can't even manage to share a bathroom. When they mature, they float off into the water, and soon are full-grown jellyfish, or medusa, and the whole beautiful cycle begins again.
Along with there being boy and girl jellyfish, which I bet you didn't know, there are also jellyfish with eyes. Do you find this as disturbing as I do? The box jellyfish, which is among the most venomous species on earth, has up to twenty-four eyes, is capable of fast directional swimming, and can even form memories. In other words, it can see you, chase you, and think about you.