Parasites, synesthesia and Daniel Tammet.
When I heard mention of the fish parasite, a picture flashed in the slide show of my mind. Like Rebecca said, once you have seen the photo, you can't unsee it.
I'll bring up calendars and synesthesia again. Time having shape seems to be a common thing. I had a conversation about this a while ago with some friends. Most had some sort of shape associated with the calendar or numbers. To me, January starts at the top and the following months fall lower until August or September lie at the bottom. The months then climb back up until they reach December. My friend has an elaborate mental grid that represents a number line. 1-100 are the main body, 101-999 go off at a right angle with a different scale, an so on.
Where does a mental model end and synesthesia begin?
Rebecca mentions mating Daniel Tammet with a woman math genius to produce a little math geniuses (Eugenics War anyone?). Just remember that Mr. Tammet is a confirmed homo. Although this doesn't preclude him from reproducing, I had to point it out. Just as lots of straight people get upset if one of their heroes is mislabeled gay, we gay folks hate it when a gay hero is presumed to be hetero.