Stalagmites and stalactites are amazing formations.

If you’ve ever walked through caves, you have likely seen dozens, or even hundreds, of them growing out of the ground or hanging off the ceiling. Just because they are common, however, does not mean that they were formed easily.

Stalagmites form when water works its way down from the surface into the cave and then drips down onto the floor of the cave. The minerals in that water solidify on the ground, slowly building up.

Stalactites form when the minerals from that same type of water solidify on the roof of the cave, and they eventually hang down. They look similar to icecyles.

Both of these formations can be quite large, and since they grow at extraordinarily slow rates, it is easy to see how they can get really old. In general, they will form at a rate of just a few centimeters in thousands of years.

The oldest stalagmite ever recorded, for example, was found in the cave system known as Richards Spur in Oklahoma. The caves are made of limestone, and in addition to very old stalagmites and stalactites, there are also lots of well-preserved fossils in the area.

The oldest one, according to a 2010 study, is 289 million years old. Pieces of it that broke off were radiometrically dated to have formed all those millions of years ago.

If you are looking at any of these types of formations, however, you can be pretty confident that it first started growing thousands of years ago at the very least. Many of the largest ones in cave systems around the world will be many millions of years old.

One thing to keep in mind, however, is that even though these formations look like hard rock, they are actually quite fragile. So, never touch them.

If you break off even a small piece, you might have broken off hundreds of thousands of years of minerals breaking up, changing their shape forever.

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