Bats and stalactites like to hang out in caves. Those pointed pieces of rock that dangle from the roof of a cave are called stalactites. Most stalactites are primarily made of limestone or lava. Bats? Flesh and blood.
Stalactites are the mineral formations that hang down like rock icicles, while stalagmites rise up from the floor. The word stalactite comes from the Greek word for "dripping," stalaktos, which in turn comes from the verb stalassein, "to trickle," which is how stalactites are formed. Water comes down through the top of the cave, bringing rock minerals with it that eventually form those pointy stalactites.