This is a great question, but it's actually quite tricky to answer definitively. There isn't one single "new discovery" that scientists made after investigating mountains in the Atlantic Ocean.

Here's why:

* The Atlantic Ocean has many mountains! We're talking about the Mid-Atlantic Ridge, a massive underwater mountain range that runs the length of the ocean.

* Research is ongoing. Scientists are constantly learning new things about the Mid-Atlantic Ridge and other underwater mountains.

However, here are some general areas of discovery that scientists have made through their research:

* Plate Tectonics: The Mid-Atlantic Ridge is a prime example of how new ocean floor is created at divergent plate boundaries. The mountains are formed by magma pushing up from the Earth's mantle.

* Hydrothermal Vents: Deep-sea vents, found near volcanic activity on the ocean floor, were discovered in the 1970s. These vents release hot, mineral-rich water, and scientists found surprising ecosystems thriving around them.

* Biodiversity: The discovery of hydrothermal vents led to the realization that the ocean depths are far more biodiverse than previously thought. Scientists continue to find new species and ecosystems living in these environments.

* Ancient Climate and Geology: Studying the rocks and sediments found on and around the Mid-Atlantic Ridge provides insights into the Earth's geological past and how climate has changed over time.

So, instead of one single discovery, think of it as a vast and ongoing journey of scientific exploration.