Molly Miller, Scartella cristata, is also known as Barnacle Blenny or Lawnmower Blenny. These blennies are very active and are always hopping from one perch to another. They are pretty peaceful fish and only reach a maximum size of 4 inches. They range quite a bit in coloration, from green, yellow and brown to almost a red coloration. They are not picky eaters and will readily eat meaty frozen foods, pellet foods along with algae. Part of the reason that some people call them Lawnmower Blennies is their love for algae. If your tank does not have algae, you may want to supplement its diet with some dried algae or some sort of food with an algae blend so that it gets all the nutrients it needs. They are mostly peaceful fish, but have been know to show some aggression to its own type. It is mostly a short lived show of dominance and not a serious fight between each other. We keep multiple blennies in tanks and have never noticed any damage to the fish due this little spat so I guess they work it out pretty quickly.
For more information on them check out this helpful link on Molly Millers: