There’s no denying that a piece of Glacier National Park lives on in every visitor, but some people — illegally — literally take a piece of the Park with them when they leave.

A recent Facebook post by Glacier National Park revealed that a box of limestone rocks made its way back to Glacier after spending 14 years in Florida. A note that accompanied the rocks said, “Please return these rocks to Logan Pass where they were in 2003. Thanks!”

Visitors hiking near Logan Pass likely took the rocks as souvenirs, not realizing that in a national park, even rocks are protected and it’s illegal to keep them. Recognizing their mistake 14 years later, the people graciously mailed the rocks back to Glacier.

Park spokeswoman Lauren Alley noted that the Park employees often get packages from folks returning stuff after they realize that removing things from national parks is not permitted. Most of the packages include rocks, fossils, twigs, and even artifacts. Petrified Forest National Park sees a lot of the petrified wood taken by guests, she explained.

“We also get notes and rocks returned from children, whose parents discover them when they return from vacations,” she said. “The general message is to please leave the cool things you find in the Park in the location you found them, so that someone else can discover them.”

Particularly with pre-historic artifacts, it can be difficult to understand an object’s full significance outside of the context of its original location, so it’s very important to leave things where they’re found, Alley noted.

The “leave no trace” mantra applies: “Take nothing but pictures and leave nothing but footprints.”