It's often said that a rolling stone gathers no moss, but is this literally true? To find out, a chart was made combining Science and Googles.
The stone is shown in blue, rolling along the ground on the bottom of the chart. The amount of moss gathered is indicated by the red line above it.
As you can see, from 1800-1810 the stone actually gathers moss very quickly. However it's way too early to draw any conclusions yet because the stone has just started rolling, so it's probably not going fast enough to stop moss from gathering.
From 1810-1825 as the stone picks up speed, there is indeed a steady decline in the amount of moss gathered. Perhaps 'they' were right after all.
However from 1825-1900, despite some fluctuations, there's a steady increase in the amount of moss gathered, to the extent that by 1900 there's probably no room left on the stone for any more moss.
Unsurprisingly this overcrowding causes moss accumulation to decrease rapidly, until by 1985 the stone's popularity as a moss gathering destination has reached its lowest point.
Since then however, there has been a steady upswing in moss gathering until the present time, suggesting a renewed interest in stone-based moss accumulation.
This is probably because as the stone lost popularity among the moss population it became less densely moss-populated ('mossulated'), until it became a desirable moss-gathering venue again.
This is likely a cyclic phenomenon, as future Googles may demonstrate.
In conclusion then: does a rolling stone gather no moss? The answer would seem to be no, yes it does. Then yes, no it doesn't again, and so on.