A stalagmite is the pointed formation that rises from the floor of a cave. When you go spelunking, or cave exploring, you'll have to avoid the areas where stalagmites have formed.
Stalagmites are thin piles of mineral deposits that have fallen from the roof to the floor of a cave. They're sometimes connected to the stalactites that dangle down from the top. Because stalagmites form from drops of water combined with minerals, they get their name from the Greek stalagmos, "a dropping," and share a root with stalactite — the Greek stalassein, "to trickle."