We’ve all done it — maybe as a kid, maybe as a grown-up.

You’re playing outdoors after a winter storm, crunching through the snow and breathing in the chilled air. Then you see it — the perfect icicle.

A fresh, perfectly transparent, water-laden treat, dripping with pure H20. Just begging to be plucked and eaten. Nature’s crunchy little snack. Mother Earth’s popsicle. What could go wrong?

Video via Kristin Ashy

As it turns out, the water in that perfectly-formed icicle may not be so pure after all.

Icicles are formed when liquid water drips off of your roof, awning, or tree — and freezes before gravity takes it to the ground. This means the water that forms the icicle dripped down the surface of your roof before reaching the edge. And what’s on your roof? Likely years of dust, dirt, pollen… and poop. Bird poop.

That’s right. The transparent, tantalizing treat may have very low levels of avian fecal matter within it.

So should you run to the doctor if you’ve indulged? Purge your system of this poison? Absolutely not. There is no need, and there are no known health impacts. Take this advice as it is meant — simply something to be aware of, not a stern warning.