Because what seems a simple stalactite here is not made by calcium carbonate, but is made by opal, and one of those stalactites can require tens of millions of years to be formed.
ここで普通そうに見える 鍾乳石は 炭酸カルシウムではなく オパールでできています これ一本できるのに 何千万年かかったことでしょう