What structural description applies to galaxies Hubble revealed existing when the universe was less than a billion years old?

Generally small and likely irregular in shape

The data gathered by Hubble regarding the earliest galaxies, those observable before the universe reached one billion years of age, provided clear evidence about their developmental stage. These young galaxies had not yet undergone the extensive mergers and assembly processes that lead to the grand structures observed in the modern universe. Consequently, the findings suggest these primordial systems were typically characterized by being relatively small and lacking the organized, defined morphology seen in mature spirals or ellipticals, appearing instead to be irregular. The text contrasts them directly with the ordered structures like the Milky Way, emphasizing their immature state.