Fossils are some of the Earth’s most useful prehistoric remnants, giving us a window to the daily life of creatures which lived millions of years ago. It has become a common sight to see popular fossils such as those of Stegosaurus and Tyrannosaurus Rex in museums, but what is much less known are the many strange and bizarre fossils which paleontologists have discovered, especially recently. These fossils have been kept – whether by ash or amber or sand – in a state clear enough for us to study and learn from.
Fossilization is a complicated and time-consuming process. It normally happens when sediments are compacted under intense pressure combined with the replacement of organic matter by silica and other materials in a process referred to as petrification. Since most tissue, including skin, organs, and muscle, decays before full fossilization can occur, we mostly find bones. Though there are plenty of bones on this list, we’ve also included a host of other bizarre fossils. (Did someone say fossilized sperm? Oh, we did.) You’ll likely be shocked at some of the weird fossils on this list; ones that unfortunately don’t get as much media attention as they should, such as a turtle the size of a helicopter and an ancient arthropod orgy. Read on to discover the 25 Most Bizarre Fossils Ever Discovered.

About 74 million years ago, a Velociraptor and Protoceratops were locked in a fierce duel in present-day Mongolia. The Velociraptor plunged its rear claws deep into the neck of the Protoceratops which responded by trying to rip the former's arm off. The two were likely covered by a collapsing sand dune, fossilized in fighting stances that paleontologists amazingly discovered while digging them up.
Though researchers most often find bones of fossilized animals, diggers in Antarctica found something even weirder: sperm. Dating back 50 million years, the sperm is attributed to a collared worm and is the oldest animal sperm yet discovered. Though such organic matter would normally easily break down, the worm's reproductive methods of shooting the sperm and eggs into a protective cocoon helped preserve this bizarre fossil discovery for ages.
Scientists have discovered a 500 million year-old eye in southern Australia. The delicately-preserved compound eye (like a fly's) has about 3,000 lenses, significantly better than the majority of its fellow creatures at the time. Paleontologists aren't sure which animal it belongs to, but it does show that very ancient creatures were indeed capable of having very powerful vision.
The 1994 discovery of a fossilized oviraptor sitting on her eggs changed our understanding of dinosaurs forever. Previously, it was only speculated that some dinos sat on their eggs (like today's chickens do) to incubate them. This perfectly discovered fossil from Mongolia proved the assumption to be true.
"Til death do us part" proved true for two ancient turtles. Found in an ancient volcanic lake in western Germany, these two turtles were doing the good deed as they sank deeper into the lake in coital bliss. Since it was a volcanic lake, the deeper waters were toxic to the turtles who quietly died, still locked together in the mating position, well-preserved by the highly toxic waters which did them in.
Some people are scared of frogs just because they seem gross, but if we had existed 70 million years ago, we would have been afraid of them because they could eat dinosaurs. The largest frog ever discovered, Beelzebufo ampinga (AKA the frog from hell), could grow up to 16 inches (41 cm) long and weight up to 10 pounds (4.5 kg).
It may seem unbelievable at first, but some of the most well-known African creatures likely roamed the English countryside a few thousand years ago. Legendary paleoecologist William Buckland identified the bones of a fossilized rhino and the preserved feces of then-local hyenas from 125,000 years back.
The fossils of Dimetrodon reveal one of the most intriguing dinosaurs found to date. Found largely throughout the Red Beds of Texas, Dimetrodon is notable for the large fin on its back, speculated to have helped in temperature control while potentially giving the prehistoric beast an edge in hunting.
Ancient volcanic eruptions were perfect for preserving ancient life, just as they did in Pompeii. When a volcano in Idaho erupted over 10 million years ago, the dust cloud spread for over a thousand miles. Over 200 skeletons have since been found in a Nebraskan dig site, including a young rhinoceros sucking its last bit of milk from its dead mother.
One of the most amazing fossils ever discovered is that of a snake, Sanajeh indicus, ready to dine on a newly hatched sauropod dino. Since it could neither open its mouth wide enough to eat a whole egg nor break through the 2-millimeter thick shell, the snake waited at the nest for the eggs to hatch. A landslide fell on the nest just as the Indian snake was about to feast on a newly-hatched 1.6 foot-long (0.5 m) sauropod newborn, preserving the scene for millions of years.
Though most worms look a bit phallic, Spartobranchus tenuis takes things to another level. The prehistoric worm - dating back 200 million years - has recently provided the "missing link" in the evolutionary transformation between the two branches of hemichordates (related to modern-day sea urchins and sea stars). The creature's strange and elongated shape is believed to have played a role in the species' development.
Interested in more fascinating discoveries? Check out 25 Unusual Things You Won’t Believe Were Found In A Back Yard.