QQQ has huge tech exposure, but it is not a 'tech fund' in the pure sense either. The fund's arcane weighting rules further distance it from anything close to plain vanilla large-cap or pure-play tech coverage.
During the time when Earth was forming and was in a molten state, heavy materials like iron and nickel sank to the center of the Earth's mass and lighter materials floated to the surface of the mass. The very center of what we call the core, is solid in the middle because of the increased pressure in that region.
At some point, probably within the first few hundred million years of Earth, the surface down to a depth of about 500 km became so hot that iron (a plentiful element) started to melt. The molten iron collected and began to sink under its own great weight.