Stalactite
A stalactite (UK: , US: ; from Ancient Greek σταλακτός (stalaktós) 'dripping', from σταλάσσειν (stalássein) 'to drip') is a mineral formation that hangs from the ceiling of caves, hot springs, or man-made structures such as bridges and mines. Any material that is soluble and that can be deposited as a colloid, or is in suspension, or is capable of being melted, may form a stalactite.