We noticed the first one a couple of weeks ago or so. A deposit of dark, rich, fertile soil plopped right outside our back gate. Maybe a foot or so in diameter, with a short conical shape.
It was like a crop circle in its mystery, this pile of dirt. And even more mysterious was that, every other day or so, it would grow. The pile was made bigger by another layer of dark soil. And other piles began to sprout up, seemingly while we were all asleep.
We pondered this pondersome puzzling pile. Was someone doing some landscaping and depositing shovelfulls of dirt outside our fence at night? (Magnum's paranoid thought). That's nutty, why would anyone do such a weird thing? (My put-yourself-in-those-shoes thought).
And I know I've seen such piles strewn about during my wanderings around the wild places of the neighborhood. Just never right at the threshold of our gate. I figured some sort of creature from the family of rodentia was making them.
A little detective work later, and I think I know the culprit. MOLES! AHA! They are molehills. I'm pretty sure.
Then I was curious. I don't think I've ever seen an actual mole. I did some more detective work to learn more about them.
I learned that if a mole changes size, shape or color, or a new one develops in adult life it should be evaluated by a doctor or preferably by a dermatologist.
I learned that the mole is defined as the amount of substance of a system which contains as many "elemental entities" as there are atoms in 12 g of carbon-12.
From that, I vaguely remembered that Avogadro's number, or 6.02214179(30)×10^23, is the number of "elementary entities" in one mole.
And that adult moles are about the size of a chipmunk.
So much knowledge from a pile of dirt.