Here is a concise summary of the provided text:
**Title:** The Mysterious Mariana Trench: Unveiling its Secrets and Inhabitants
**Summary:**
* The Mariana Trench, the deepest point on Earth (11,000m), is a largely unexplored environment.
* Despite initial beliefs, life thrives in the Trench, including unknown species, giant invertebrates, and bizarre creatures.
* Historic expeditions (1958, 1960, 1985) revealed:
+ Unexpected life at extreme depths.
+ A disc-shaped, maneuverable object observed by Jacques Piccard's team (1960).
+ Unexplained sounds and a damaged probe in 1985, potentially attributed to a massive, unknown creature.
+ A theory suggests the Megalodon, a prehistoric shark thought extinct, might have survived in the Trench.
* Recent discoveries include a bioluminescent, alien-like jellyfish (at 3,700m depth).
* The text concludes by highlighting the ocean's vast, unexplored mysteries, suggesting that the search for "alien" life might be more fruitful underwater than in space.
Here are the key facts extracted from the text, excluding opinions, with each fact numbered and presented in short sentences:
1. **Location**: The Mariana Trench is located west of the Pacific Ocean, near the Mariana Islands.
2. **Depth and Length**: The Mariana Trench is approximately 150 kilometers long and more than 11,000 meters deep.
3. **Comparison to Everest**: The trench is so deep that Mount Everest could sink into it with almost a kilometer of water left to reach the surface.
4. **Discovery of Life**: In 1958, scientists discovered life at a depth of about 7,000 meters in the Mariana Trench.
5. **Types of Life Found**: Life forms include bacteria, invertebrates, mollusks, and enormous unidentified creatures.
6. **First Expedition to the Bottom**: In 1960, Jacques Piccard and his companion reached the bottom of the trench in the bathyscaphe Trieste.
7. **Challenger Abyss**: The deepest point in the Mariana Trench is called the Challenger Abyss, located 11,000 meters below sea level.
8. **Pressure at the Bottom**: The pressure at the bottom is approximately 3 tons per square centimeter, 100,000 times stronger than the atmosphere at normal sea level.
9. **1985 Incident**: The crew of the American ship Glover Challenger encountered strange occurrences while studying the trench, including unexplained sounds.
10. **Probe Damage**: A 9-meter spherical device (Hedgehog) was severely damaged, with bite marks and torn cables, after being lowered to the depths.
11. **Official vs. Actual Cause of Damage**: The official report cited a collision with a rock, but crew members and the absence of rocks in the area suggest otherwise.
12. **Megalodon Theory**: Biologists suggested that the damage could have been caused by a megalodon, a prehistoric shark thought to be extinct.
13. **Characteristics of Megalodon**: Estimated to weigh 50 tons and measure 22 meters in length, with a gigantic tooth (size of a man's hand) previously found.
14. **Recent Expedition Discoveries**: A recent expedition discovered a jellyfish with a brightly shining body and long tentacles, unlike any known species.
15. **Location of Jellyfish Discovery**: The jellyfish was found in a little-known area of the Mariana Trench called the "Underwater Enigma Peak" at a depth of 3,700 meters.