The mysterious mural on Mount Chiliad seems to indicate a larger mystery going on under the Los Santos' surface. Part of the mural, the lighting around the outline of the mountain points to the needed visit to the summit late at night during a storm to witness another UFO appear (which the player cannot even seem to interact with), has already been decoded.
The decoding of this second part of the mural leads players to believe that the other symbols must also be broken down similarly before the mystery can finally be solved.
The drawing is confirmed to indicate that a total of four UFOs can be found dotted on the world map. The first saucer appears on the summit. The second spaceship appears high above Fort Zancudo after 100% completion of GTA 5's single player campaign. The third can be found under the Sandy Shores hippy commune/UFO shrine and the fourth is submerged under the ocean.
Glyphs related to UFOs are found all over the world, particularly at the Sandy Shores hippie camp and scary Altruist mountain hideaway, ringed in alien code that can possibly be decrypted as well. This maddening mystery still remains unclear but if the mural is anything, it just has to be involve a UFO, an egg or a jetpack.
The scientology-inspired Epsilon cult may have money on top of their priority but it appears they also have an inside scoop to some weird information in Los Santos. They might even be connected to it somehow. If you pursue the Epsilon side missions "Seeking the Truth" with Michael, it will lead you to a crazy cultist Marnie in an alleyway, scrawling these words of graffiti on walls:
Dream the impossible
Dream! Of a planet of
Fire and a dinosaur
With a saddle. If not
For me who am i?
Spaceship earth over-
Population means breakdown
The fruit tree is a lie.
It seems nonsense at this time but players believe this can relate to the overarching Mount Chiliad mystery and that the dinosaur might reference the egg drawing on the mountain mural. What do you think?