79 Times People Found Interesting Fossils And Asked Others To Identify Them

The word “fossil” literally means “dug up,” taken from the Latin word fossilis. According to the Australian Museum, a fossil is any remains or trace of past life preserved in rock—the actual tissues, shells, teeth, or bones of a plant or animal, or even just the footprint it left behind in ancient mud.

What makes fossils so valuable is the story they tell. As the British Geological Survey explains, they show us where life on Earth came from and how our environment has changed over geological time. They’ve also helped scientists understand that continents now separated by vast oceans were once connected.

Geologists even use fossils to date rock layers. Through evolution, different species appear in rocks of different ages, which gives scientists a reliable timeline to work with. Ammonites are a great example. They're so reliably tied to specific geological periods that scientists can use them to figure out the age of rock strata in completely different parts of the world.

As for how fossils actually form, the Australian Museum notes that it usually starts with an organism perishing and getting quickly buried under sediment, like mud, sand, or volcanic ash.

The soft parts typically decompose, leaving only the harder bones or shells. In special cases though, even soft tissue can survive—if, for example, the organism got trapped in amber.

From there, more sediment builds up over time, everything gradually hardens into rock, and there the creature sits. It is only when erosion slowly wears the rock back down that these once-living organisms are revealed to us from within the stones.

The odds of any of this happening are pretty slim. The Natural History Museum warns that the vast majority of living things simply rot away without leaving any trace behind. So stumbling across a fossil is genuinely lucky.

Nearly all the fossils we find—around 99%—come from marine animals like shellfish and sharks, since the ocean floor was ideal for quick burial. Once remains are covered by sediment, decomposition slows down significantly due to the lack of oxygen, giving fossilisation enough time to take hold.

Land animals had a much harder path to preservation. Most dinosaur fossils, for instance, come from animals that happened to live near rivers or lakes.

As dinosaur researcher Dr. David Button from the Natural History Museum explains, many perished shortly before flooding covered their remains in mud and silt, while others were washed into rivers by heavy rain.