NASA says it best: "Neutron Stars Are Weird!"
They are extraordinarily compact. Just a sugar cube-sized piece of this extremely dense material — the remnants of a collapsed, exploded star — weighs 1 billion tons. They're known to rotate quickly, but scientists just found an extreme example of a neutron star spinning faster than a blender:
716 times per second. You read that right.
"If future observations confirm this, the 4U 1820-30 neutron star would be one of the fastest-spinning objects ever observed in the universe...