You're out hiking in the desert or on the Colorado National Monument and you see some black stuff on the dirt. What the heck is it?

It's called biocrust and it feeds the plants in the desert.

And you should never ever step on it.

The actual name is biological soil crust and its importance cannot be overstated. Made up of various biological components, biocrust is where the plants in the desert get their food. While they have adapted themselves to living in the desert there is one thing they can't do.

Survive footprints.

The reason our desert looks the way it does is because of biocrust. When it rains, it feeds the plants and binds the soil together, keeping the enriched soil in place. When a person walks through it, it disrupts that balance and can cause nearby plants to die off due to the lack of nutrients being fed to it. Biocrust can take up to 250 years to recover from just one footprint.

So when you are out hiking in the desert and you see it, stay away from it. And when you see those signs that tell you to not walk on it, don't.