What are some great facts about the ocean

10 weird facts about Earth you (probably) don't know yet

The largest living thing is a giant mushroom

When it comes to the largest creature on earth, most people might think of blue whales, elephants or trees. Some might also point to coral reefs as the largest accumulation of living things.

But the largest, single organism known to us is a honey mushroom (Armillaria) in the US state of Oregon. In 1992, one such mushroom covered 15 acres in Michigan. When a mysterious tree death was recently investigated, a research team discovered that the culprit was an even more gigantic mushroom that covers at least 809 hectares and is estimated to be thousands of years old.

The mushrooms themselves sprout from the ground, but are connected by an underground network of tissue called mycelia. Chances are the mushroom's offshoots aren't perfect clones, but the gigantic mushroom still seems to deserve a size trophy (and apparently it tastes great with spaghetti).

Some parts look pretty extraterrestrial

The Danakil Depression in Ethiopia is a bizarre landscape that deserves a whole series of superlatives: Hottest. Driest. Deepest. Strangest. Although the simmering hot springs, poisonous gases, crackling lava lakes and salty mirages make the Danakil Depression seem like one of the most inhospitable places on earth, life itself has found a way here. In the colorful hydrothermal springs one can find ecosystems that astrobiologists are currently using as analog models for the search for life outside the earth.

There is an island with a "waterfall under water"

The southwest coast of Mauritius appears to be on the edge of an underwater waterfall. But the abyss that is looming there is only an illusion. The swirling ocean currents carry silt and sand with them, creating the frightening pattern that emerges on the actually harmless ocean floor. Seen from above, the sight looks spectacular and can even be admired on Google Earth.

There are treasures hidden beneath our feet

About 300 meters below the floor of Mexico, the aptly named Cave of Crystals is home to the largest known natural crystals in the world. Some of the giant selenite crystals are over nine meters long. You'd think it wouldn't be easy to keep such a cave hidden for a long time. But it wasn't actually discovered until 2000 when miners at a silver mine accidentally broke the cave wall.

A similarly magical, underground treasure is the Sơn-Đoòng Cave in Vietnam. Although it is the largest cave in the world, it was also still unknown until 1991. There's a lush rainforest inside the cave, and it's so big that a Boeing 747 could easily park in it.

Some of the clouds are alive

Sometimes dark clouds appear near the ground during dusk, changing their shape. As they swirl and change, they seem to be alive - and they are. They are made up of hundreds of thousands of starlings that fly in unison. The phenomenon is known as formation flight or murmuration. Scientists suspect that the birds make these hypnotic movements when avoiding predators or looking for a place to sleep. But it is still a mystery how exactly they manage to perform these acrobatic flight maneuvers synchronously.

There is an underwater meadow

Who is the oldest of them all?

The most common seaweed in the Mediterranean, the Neptune grass (Posidonia oceanica), was named after the Greek god of the sea. It is believed that it is one of the oldest known organisms on earth. Genetic sequencing recently revealed that the seagrass meadow off the coast of Spain could be up to 100,000 years old.

This means that the first stalks of seagrass took root and began the process of cell division and cloning when the ancestors of modern humans had not even left Africa. One of the reasons why this is slow growing Posidonia survived so long is the fact that this grass has so little competition and hardly any predators. Only humans are slowly destroying the habitat of the ancient seagrass through poor marine management and the exploding population.

One of the rivers is boiling

It was once believed to be a legend, but deeply hidden in the Peruvian Amazon there is a boiling river. Basically, it's not really boiling, just moving a few degrees below the boiling point. But the water is hot enough to turn the already strange rainforest into a steamy, mystical paradise and to cook awkward animals alive.

Recently, National Geographic Explorer Andrés Ruzo visited the boiling river and returned with a reason for its exuberant temper: enormous geothermal activity unrelated to volcanic activity or oil drilling.