Ancient Reefs Built Entire Mountain Ranges
Tiny marine organisms called rudist bivalves once constructed massive reef systems that later became towering mountain ranges when tectonic plates lifted the seabed. These ancient builders thrived for over 100 million years before vanishing alongside the dinosaurs. Their fossilized remains still form the stone foundations of parts of the Alps and other ranges today.
💡 Fun detail:
Some of the limestone used in famous European cathedrals is actually made from the shells of these long-extinct reef creatures.
Source: Natural History Museum