Waitomo Glowworm Caves, Waitomo, North Island, New Zealand

The stalactites, stalagmites, and other cave formations grew from water dripping from the ceiling or flowing over the walls and leaving behind limestone deposits. The stalagmites form upward from the floor while the stalactites form from the ceiling. When these formations connect they are called pillars or columns and if they twist around each other they are called helicti. These cave decorations take millions of years to form given that the average stalactite grows one cubic centimetre every 100 years.
Biology
The most renowned animal in the cave is the glowworm Arachnocampa luminosa. There are several small underwater lakes that were created by freshwater creeks or brooks.