Actun Tunichil Muknal (Cave of the Crystal Sepulchre), is about an hour and a half from Belize city notable as a Maya archaeological site that includes skeletons, ceramics, and stoneware. There are several areas of skeletal remains in the main chamber. The best known is "The Crystal Maiden", the skeleton of a teenage girl, possibly a sacrifice victim, whose bones have been calcified to a sparkling, crystallized appearance cemented in the limestone. The ceramics at the site are significant partly because they are marked with "kill holes", which indicates they were used for ceremonial purposes. Many of the Mayan artefacts and remains are completely calcified to the cave floor. One artefact named the “Monkey Pot” is one of just four found in Central America. The Mayans also modified cave formations here, in some instances to create altars for the offerings, in others to create silhouettes of faces and animals, or to project a shadow image into the cave. The cave is extensively decorated with cave formations in the upper passages and is considered the best cave to visit while in Belize.