“To enter the tunnel, you force yourself between jutting, fang-like speleothems, giving you the unnerving impression that you are entering the maw of some horrible, burrowing worm.”
Speleothem is the collective word for various mineral growths found in natural caves. These growths are formed when water evaporates, leaving behind minerals. There are six major types of speleothems: stalagmites, stalactites, columns, flowstone, draperies, and straws.
Remember, stalactites are stuck TITE to the ceiling!
Speleothem comes from the Latin word spelunca, which itself comes from the Greek word speleios, which means cave. Thema is a Greek word meaning deposit.
Image courtesy of Wikipedia. Learn more at http://en.wikipedia.org/wiki/Speleothem