Once upon a time, God got fed up with the way mankind was progressing, and decided to wipe them out by drowning and start again.
He didn't want to spend time on re-creating all the animals and birds again, so he contacted the only good man he could find, and told him to build a survival ark and fill it with a breeding pair of all the creatures on Earth.
Well, Noah built his ship, and duly filled it up with pairs of all the animals and birds he could find. Unfortunately he missed out on the dragons and unicorns, who were too busy doing their own thing to want to be cooped up on a boat with other minor animals.
In due course the rains came and flooded the Earth, wiping out all the sinful mankind.
One thing that Noah hadn't considered was all the caca that the animals produced.
The ark was becalmed for a long time in one part of the flooded Earth, and every day Noah and his missus had to shovel all that caca into the ocean.
This pile of caca got ever greater, until the floods finally receded, and the winds got up, and Noah was able to all the animals go free and get on with their lives.
As the floods receded, the pile of caca emerged from the floods.
And there it remained, until it was finally discovered by Christopher Columbus.