Earth was at the verge of destruction.
Environment was being damaged.
Number of forests was decreasing rapidly.
Glaciers were melting rapidly.
Species of animals were at the verge of extinction.
Oceans were polluted heavily.
Aquatic species were fighting survival war.
In such circumstances aliens descended on earth as saviors.
They made environment better.
Planted trees, increased forests
Made oceans free of pollution
Stopped melting of glaciers
Increased the number of endangered species
And before doing all this!!
They wipe out the human race from the face of the Earth!!!
