I've had some fun time looking at some plate-tectonics sites, looking at how the Earth's land surface looked over the last billion years or so.

But there appears to be no evidence of plate tectonics elsewhere in the Solar System. Mars has some almost plate tectonics, but that may be because it is smaller, meaning less internal heat to drive it. Venus has the same mass and density as the Earth, but no sign of plate tectonics.

Could Earth's liquid-water supply have affected rocks' mineralogy in a way that would make plate tectonics possible? That would account for the difference between Earth and Venus, since Venus's liquid water resides in its high cloud layers.