Visited a large cave called Ryugado, near the city of Kochi. I doubt the name means anything special, probably something like "sponsored by Disney", or "no dry-cleaning facilities available here". The part that is open to the public is about 1 km long. I've been to hundreds of caves all over Europe, but Ryugado was still very impressive. The only bad thing about the cave was that every 10 metres or so you would come to a Japanese woman sitting on a stool who would shout a bunch of crap in Japanese. This was utterly pointless because everything they said about that particular part of the cave was written in the leaflet anyway.
The cave was discovered about 70 years ago. The people who discovered it decided to leave a vase under a stalactite to see if, over a period of many years, it would become completely covered with limestone. The rather obvious answer to this question is yes, things do get covered in limestone if you leave them for 70 years under a stream of dissolved limestone. Fuckwits.