I heard that in the center of the earth there is .....?

The substance you're talking about is neutronium which is what the singularity of a black hole is supposed to be made of.

The center of the earth is the molten nickel/iron core, the compression required to create neutronium is impossible to create even with the pressure of earth's crust, mantle, and outer core pressing into the inner core.

To make neutronium you basically have to make the substance even more dense than the crust of a neutron star. The crust of a neutron star is made of neutrons that are side by side pressed together. They're formed when a star collapses and the outer crust of the star is enough to overcome the electron degenerate pressure.

The electron degenerate pressure is the repulsion of the outer layers by the mutual repulsion of the electrons within the atoms as the outer layers try to squeeze the electrons together by its cumulative pressure.

If the outer layer of the star are greater or equal to 1.4 solar masses the electron degenerate pressure breaks down and the electrons are squeezed into the nucleus of atom and merge with the protons and become neutrons so the density of a neutron star is enormous.

The reason is because atoms are mostly empty space the electrons have a massive amount of distance from the nucleus of the atom. When 2 atoms are joined they're joined by the outermost shell of their electron orbits.

In a neutron star the nuclei are pressed up against each other tightly. 1 tsp of the crust of a neutron star is as massive as a mountain range...to give you an idea of the density. When the outer layers exceed 3 solar masses total then the neutron degenerate pressure (mutual repulsion of the neutrons based on the quantum physics law stating that matter can't occupy the same space at the same time) breaks down and the neutrons are therefore squeezed into each other and it becomes theoretically neutronium, the substance of a black hole singularity.

No atom that we're aware of in existance can have the number of protons you're referring to, and any substance that dense probably couldn't exist in the earth's core.

I didn't find anything on the internet when I typed in strangium so I would say it isn't true. If it is then it must be called something else. That isn't the right name.

IVE HEARD OF STRONTIUM90 RADIOACTIVE