It gives off so much light that it can be seen even from space. People in the old days used its light to send signals back and forth with others far away.
(From Bulbapedia )
Ampharos is a yellow, bipedal Pokémon with a white belly. It has conical ears with black stripes and a red orb on its forehead. Its long neck has several black rings around it near the base. Its stubby arms resemble flippers and each foot has a single white nail. It has a long, black-striped tail with a red orb at the tip. The orb on its tail can shine so bright, that it can be seen from space. People have used the light as a beacon, or to send signals across the ocean. Ampharos is generally found in grasslands.
As Mega Ampharos, its toes turn black and it grows white wool at the back of its head and over its tail. Its long woolly tail has many small, red orbs attached to it. Its conical ears retain their stripes, but are now segmented with swirled tips. When it increases the amount of electrical energy within itself, the red orbs on its body and wool emit a strong light.
(From Bulbapedia) Ampharos resembles a sheared sheep that its evolution line leads up to as they lose wool with each evolution. It also shares traits with a lighthouse, such as its height, stripes and the beacon on the top; the two also share a name. It, as well as its pre-evolutions, may have been based on the title of the science fiction novel Do Androids Dream of Electric Sheep?.
(From Bulbapedia) Ampharos is a combination of ampere or amp (a measure of electrical current) and pharos (Greek for lighthouse).