Yes, I really meant lawnmower but in reality it is:
The Sailfin/Algae Blenny is notable for its unique looks and winning personality. With a mottled tan color, oversized eyes, and typical body shape of the Blenniidae family, Salarias fasciatus adds visual appeal to any marine aquarium. But despite its tendency to grow to an impressive 5" in size in the home aquarium, the Sailfin/Algae Blenny remains peaceful, active and, therefore, fun to observe.
Also referred to as the Jewelled Rockskipper, Lawnmower, or Rock Blenny.