Final answer:
Dwarf elliptical galaxies are the most common type of galaxy in the nearby universe and consist mostly of old stars. Galaxies in the early universe were small and likely merged to form larger galaxies. This merging process was more common in the early universe compared to now.
Step-by-step explanation:
Dwarf elliptical galaxies are probably the most common type of galaxy in the nearby universe. They consist almost entirely of old stars, with very little interstellar matter, and have smaller masses compared to spiral galaxies like the Milky Way. These dwarf ellipticals, which range in size to even smaller than some spiral galaxies, also show that galaxies may change their appearance and structure over time due to collisions with other galaxies or changes in the rate of star formation.
In the early universe, as seen in Hubble Space Telescope images, galaxies were often under construction—smaller groupings of stars that would likely collide and merge to form larger, more stable galaxies. These primordial galaxies emitted light about 11 billion years ago and were significantly smaller than the galaxies we are familiar with, like the Milky Way, suggesting that this construction and merging process was common in the early universe but is less prevalent in the present day.