Just to put the time scale into the picture for you, the 'tubes' which are small stalagtites hanging from the ceiling take hundreds of years to form, the longer stalagmites and stalagtites (that don't join) take thousands of years, the columns (stalagmites and stalagtites that join up) take tens of thousands of years, and the white flowstone in the first photo forming a large block take hundreds of thousands of years to form.