1. Proto-stalactite in which water flow down through the center of the straw. Upon entering a vadose cave passage, the change in the partial pressure of carbon dioxide cause CO2 degassing and the slow precipitation of CaCO3. The straw grows downwards as a result; water also flows down the outside of the straw causing the stalactite to grow outwards around the straw. 2. American name for straw stalactite [9].