Obviously the name of this is a bit of a joke referencing the “Egg of Coot” from Arneson’s “The First Fantasy Campaign” (which some people take to be an attack on Mr Gygax, but was in fact aimed at Gregg Scott, head of Microarmor at the time).
An insanely large egg lies underground here, partially exposed by a small underground river and further excavations by parties unknown.
Some like to think it was a dragon’s egg. But the scale makes that unlikely at best – what dragon could lay a 140 foot long egg? Even guesses about the tarrasque’s reproductive cycle get caught up by the size of this shell.
Of course, the point is pretty much moot now, because unknown forces have cracked the egg and consumed whatever was within.
But there are strange things afoot in the nearest village, and the six-eyed sage of the Amber Hills claims that the egg was the embryo of a god. And whoever ate it might have left enough yolk behind for some of the children to have found it and played with it or even eaten it…