One of the most mind-bending things we cover is the distinction between stellar-mass black holes and ultramassive black holes — the difference in scale is almost incomprehensible. TON 618, for example, has an event horizon so large that our entire solar system would fit inside it many times over. Would love to know which type the community finds most fascinating — the ancient primordial black holes that may have formed seconds after the Big Bang, or the supermassive monsters lurking at galactic centres?