A stalagmite is a cone-shaped rock formation that grows upward from the floor of a cave. While stalactites hang down from cave ceilings like icicles, stalagmites build up from below, created by mineral-rich water dripping from above.

Here's how they form: as water seeps through rock and drips into a cave, it leaves behind tiny deposits of minerals, especially calcium carbonate. Drop by drop, year after year, these minerals pile up like wax dripping down a candle, except building upward instead. A single stalagmite might take thousands of years to grow just one inch.

Sometimes a stalagmite and a stalactite meet in the middle to form a column connecting floor to ceiling. Cave explorers love finding these formations because they create underground landscapes that look like stone forests or alien worlds.

To remember which is which: stalagmite has an “m” for “mound” and grows up from the ground, while stalactite has a “t” for “top” and hangs from the ceiling. When you visit a limestone cave, the impressive pillars rising from the cave floor are stalagmites, each one a testament to the patient, persistent work of dripping water over thousands of years.