Elder's Moonstone

The Elder's Moonstone creates a circular pillar of light that can mark a spot on the ground.

Source
Elder's Moonstones are one of the two alternate items found in Lucky Red Envelope sent in the mail to you after visiting each Elder during the Lunar Festival. The odds of getting either appear to be about even.

Use
Using an Elder's Moonstone produces a circular pillar of light matching that seen around the Elders, found during the Lunar Festival. This is the same effect as that of the Elune Stone, produced by Elune's Lantern.

It can be useful for marking points in a dungeon while in a group or raid, e.g. marking tank positions. Neither the light produced by stone nor the use of the stone creates any threat.

They can also be used as props for floor shows and fashion shows.