Was just wondering about the origin of lava rocks. Does anyone have any information on them? I'm currently holidaying in Japan and spent the last couple of nights at Lake Kawaguchi, some distance away from Mount Fuji.

I happened to be staying directly across this place:
Attachment 49033

On closer inspection:
Attachment 49034

Realized that it was:
Attachment 49038

Rocks galore:
Attachment 49036
Attachment 49037

So if anyone knows the origin of the lava rocks we see in aquariums, it'll be very helpful in quenching this recent obsession with lava rocks. I've been seeing it everywhere in Japan and have a ton of inspiration (or poison) for setting up new scapes!