Back in the 5th or 6th grade my science teacher was telling the class about sharks. She said something about how sharks are an example of a perfected product of evolution, and that some sharks have been around basically unchanged for thousands of years. I'm now quite sure that she meant, some species of shark. But at the time, I thought:
If she meant "species," surely she would have said "species." Therefore, if she didn't, by modus tollens, she must mean that some individual sharks have been around for thousands of years. Unchanging. Undying. All-consuming.
I'm sure that this was like many subtle childhood misunderstandings, insofar as it didn't affect my day-to-day life very much. I don't interact with elderly sharks very often. I've never had to take a shark's vital readings, or card a shark at a bar. There's basically nothing in my life where I would need to know how old a shark is. Until Freshman year of college, that is.
In Freshman Lab (non-Johnnies can think of it as intro biology), my tutor (professor) Mr. K made some point about aging - in particular, about how animals that reproduce sexually instead of by cell division don't destroy the original in the process of making copies. He noted that it seems like all such animals have a natural aging process. They only get so old before they start declining with age, and they can only age so long before they die. But I had the perfect counterexample.
"Excuse me," I said, "but what about sharks?"
"Well, what about sharks?" responded Mr. K.
"We all know that sharks are immortal, right?"