Galatea was found in late July 1989 from the images taken by the Voyager 2probe. It was given the designation S/1989 N 4. The discovery was said (IAUC 4824) on August 2, 1989, but the text only talks of "10 frames taken over 5 days", giving a discovery date of sometime before July 28. The name was given on 16 September 1991.
It is not a sphere and shows no sign of any geological changes.