... The deepest drill hole ever completed is around 12 km deep, and it showed that rocks at that depth are still solid. Volcanoes erupting liquid lava on surface shows that there must be liquid somewhere in the Earth. Beyond 12 km in depth, we know very little about the Earth's internal composition and structure.
The largest elliptical galaxy are likely the product of galaxy merger as we have it in one of the largest galaxy mergers ever observed consisting of four elliptical galaxies in the cluster CL0958+4702. It may form one of the largest galaxies in the Universe.