Moai statue

Moai statues are a type of structure seen on Easter Island. They are huge rock structures carved to resemble vaguely human faces. Although they exist in real life, they make cameos in Konami games as well.

Relation to the Metal Gear series
Because the Metal Gear franchise was produced by Konami, a Moai statue makes a frequent cameo in some of the games:

In Metal Gear Solid, the Moai statue can be found in basement 2 of the warhead storage building.

In Metal Gear Solid 2: Sons of Liberty, the Moai statue can be found in various locations on the Big Shell during the Big Shell chapter, one of which requires that the player play in Extreme mode.

In the Deja Vu mission for the PS3/PS4 versions of Metal Gear Solid V: Ground Zeroes, the player has to find a Moai statue in the admin building's basement to recreate a scene from Metal Gear Solid.