For a hundred years the best mathematical minds thought knot 1 and knot 2 in the background were two different knots until K Perko in 1973 found they were one and the same. Who would have guessed? Knot classification is not a simple task.
From my vantage point, knot 10.161 could also qualify as a memorable roller coaster ride!
More on the Perko pair and the Knot geometry project on Patreon