What's Inside These Ginormous Black Holes?

Did you hear? Scientists have discovered something wild: the biggest black holes EVER! They're lurking out in space—giant, gaping, sucking maws of gravitational force from which not even light can escape. It's weird! It's mysterious! And if we think about it too much, we get this funny feeling like our brains are turning into puree! But while it's all well and good to ponder the mind-liquefying enormity of the whole entire universe, there's an even bigger mystery to discuss: what could be hidden inside the black holes?
...Just kidding, we know exactly what's in there.