It is most likely a sand sifter, though hard to tell for sure. It will sift the sand, eating the actual sand (it is imperative to have the appropriate substrate) and digesting bacteria and organic matter from the surface or between particles.
It is NOT an "algae eater" per se. It will not eat algae off glass and rocks. It is possiblle that it could help control issues with algae on substrate, but it is a slow mover and may not even cover the whole tank.
Algae problems are definitely best addressed by finding the root cause (often nutrient load) and not adding animals. In a small tank, it will starve, adding to problems. These cukes (making an assumption here as the pic isn't completely clear) are nice members of a clean up crew in appropriate tanks. But they will not resolve significant problems