Imagine your awe if you stumbled upon a 60-million-year-old fossil, an underground city, or an army sculpted to protect its ruler in the afterlife. Well, there have been many people who have accidentally stumbled upon enormously significant pieces of history that have helped us study and understand our ancestors in a more rigorous way. Here are 10 astounding archaeological discoveries that were purely accidental.

1 In 1902, workers broke through the roof of the Hal Saflieni Hypogeum when cutting cisterns for a housing development project in Malta. The neolithic sanctuary and necropolis had been in use since 4000 BCE, predating the pyramids and housed the remains of 7000 bodies.

In 1902, the British military naval yards in Paola, Malta attracted a large number of workers. This increased the demand for housing in the area and a number of housing development projects popped up.

During the construction of one such complex, workers cutting cisterns broke through the roof of a temple structure which would later be named “Hal Saflieni Hypogeum.”

The first excavation work was done by Fr. Emmanuel Magri from 1903 to 1906. After his death, the task was taken over by Themistocles Zammit.

The Hypogeum is a three-level Neolithic structure made of soft globigerina limestone. The uppermost level has burial chambers, the middle level has beautiful carvings and painted ceilings, and the lowest level was probably used as storage.

Amulets, pottery vessels, shell-buttons, clay beads, and the remains of 7,000 humans were recovered from the site. An examination of these grave goods established that the sanctuary had been in use from approximately 4000 BCE to 2500 BCE. (1, 2)

2 In 1986, Romanian workers were testing the ground for a power plant when they stumbled upon the Movile Cave. Life inside the cave has been separated from the outside world for the last 5.5 million years. This has developed a unique ecosystem with bizarre creatures and toxic gases.

Workers testing the ground for a power plant near Mangalia in communist Romania discovered a pitch-dark cave that has been completely sealed off from the outside world for the past 5.5 million years.

The air inside the Movile Cave, as it came to be known, is thick with harmful gases and stinks of burnt rubber and rotten eggs. Even though the cave does not receive any sunlight and water from the surface, life continues to flourish in this unique ecosystem.

The strange conditions have enabled the evolution of strange creatures. Out of the 48 species identified, 33 had never been seen by humans before. In the absence of sunlight, almost all of them are born without pigment and without eyes. Also, there are no plants, which is food for animals in the outside world.

Instead, these animals get their food from bacteria thriving in a frothy layer above the water. The water itself has been lying around in the cave for 25,000 years. (1, 2)

3 In 1979, a gold miner in Alaska discovered a well-preserved body of a bison. He named it “Blue Babe” because the bison’s mummified hide had a metallic-blue sheen. But it was no ordinary bison. Researchers found out that it was a male steppe bison that died 36,000 years ago.

Though bison is now a symbolic mammal of North America, they are relatively new to the American landscape. Their ancestor, the steppe bison, inhabited the Beringia region of Canada and crossed over to North America only some 160,000 years ago.

The permafrost in the region has ensured the discovery of well-preserved fossils. One of the most famous discoveries is that of a steppe bison that was mummified 36,000 years ago.

The Ice Age carcass was unearthed by a gold miner in a mine near Fairbanks, Alaska in July 1979. He named it “Blue Babe” because of the metallic-blue cast on the mummy’s hide. It was caused by blue iron phosphate that covered most of the preserved skin.

The well-preserved fossil with tufts of reddish-brown hair and claw marks of a Beringian lion has been on permanent display at the University of Alaska Museum. (1, 2)

4  In November 2016,  nine-year-old Jude Sparks tripped over a fossilized skull with tusks when hiking in the Las Cruces Desert in New Mexico. The remains were found to be of a 1.2- million-year-old stegomastodon, an extinct species of proboscidean that lived during the Pleistocene period. 

Jude Sparks was hiking with his family when he tripped and landed next to an unusually shaped, skeletal remains of a skull. The family decided to consult professor Peter Houde. They had seen him interviewed in a YouTube video about a similar-looking fossil.

Professor Peter Houde taught biology at New Mexico State University. He immediately recognized the picture of the remains to be of a stegomastodon.

Fossils of stegomastodon are rare to come by. They are an extinct proboscidean and belong to the family of mammoths, elephants, and mastodons.

Stegomastodon had inhabited the earth from 2.6 million to 11,700 years ago, a time period named the Pleistocene. The discovered fossil is 1.2 million years old. (source)

5 In 2011, miners at the Suncor Millennium Mine in Alberta discovered the most well-preserved fossil of an armored dinosaur during routine work. It took six years to chisel out the 18-foot-long nodosaur. The 110-million-year-old fossil was so intact that a mass of food had fossilized along with the stomach. 

Shawn Funk, a heavy-equipment operator for the Suncor Energy Company, noticed an unusual deposit whose color and texture stood out from the surrounding rock. The specimen was transported to the Royal Tyrrell Museum of Palaeontology, Alberta after the mining company informed the museum.

The fossil, which was covered in marine sediment, was identified to be of a dinosaur by museum technician Darren Tanke. It was so soft and fragile that it took nearly six years to piece together the most complete armed dinosaur, a nodosaur, on record. A mass of fossilized food was also recovered from its stomach.

The 18-foot-long, 110-million-year-old nodosaur is so well preserved that it appears to be a statute with detailed spikes. Researchers even recovered a mass of fossilized food from its stomach. The restored fossil weighs 3,000 lbs with missing hind legs and tail, swept away by miners. (source)