What did the Soviets discover in the Kola Superdeep well at a depth of 12,262 meters?

We know so little about the structure of the Earth. For example, our planet is not fully spherical, as it slightly flattens when rotating. Therefore, its equatorial diameter (12.754 km) is 43 km larger than the polar one (12.711 km). Our planet is the densest celestial body in the solar system, followed by Mercury among other planets. Different layers of our planet's core, crust, and mantle rotate at different speeds relative to each other. Oxygen makes up about 50% of the entire mass of the earth's crust, which is found in bound form in almost all minerals. About 25% of the crust is silicon, and the remaining 25% is everything else.
The continental crust is on average 35-45 km thick but it can reach 75 km under mountain ranges. The matter density in the center of the Earth's core reaches 12.5 tons per 1 m³, and the pressure there is about 3.7 million atmospheres.
Humanity has dived deep into oceans, flown to the moon, and even sent its robotic explorers to Mars. We have studied the surface of the Earth quite well, but as always the most interesting thing lies deep inside. And although these depths are literally under our feet, we know little more about them, if not less, than about the deepest space. A whole "expedition" is needed to look even a little into the earth's crust, just like flying to the moon. And there have been such projects that brought some amazing data.
Well, it's time to find out what lies deep down in the ground. Is there life out there? And what interesting things have already been found there?
Today we'll look at three of the most interesting ultra-deep wells that became one of the first projects exploring extreme depths of the earth's crust.
What was found in the deepest wells?