“Let’s see…” Sanagi put her hand to her chin and pondered. “Mr. Kousaka, have you heard of Diplozoon paradoxum?” When Kousaka shook his head no, Sanagi began explaining the ecology of that parasite. Their lifelong copulation, their appearance coming to resemble a butterfly, their fated love at first sight, the blindness of love, worms that were two peas in a pod. After talking for a while, Sanagi suddenly became aware of how talkative she was being and her face reddened, but Kousaka said “Keep talking,” so she talked a little more. “This earring.” Sanagi parted her hair to show Kousaka. “This is modeled after a parasite too.” “It just looked like a blue flower to me. So there’s a parasite shaped like that?” “Right. It’s called Kudoa septempunctata, and it belongs to the Myxozoa. These parasites use both fish and annelids as alternating hosts, and each of their spores has six to seven flower-petal-shaped structures called polar capsules, so it looks like a full flower from above. The D. paradoxum keychain is a little exaggerated, but if you dye K. septempunctata blue, it really does look exactly like this earring. Look it up.” As instructed, Kousaka did an image search for “Kudoa septempunctata” with his smartphone. And indeed, many images came up of tiny organisms under a microscope that looked just like Sanagi’s earring.