I've been looking at these in my inventory since the 2nd alpha.

[HUnewearl_Meira]

And I still have no idea what they are.

Can anyone enlighten me?

[spoiler-box]http://i43.photobucket.com/albums/e358/VanGarrett/pso2-wtfisthisstuff.jpg[/spoiler-box]

[Ryo]

Photon Drop, Grinder, Synthesizer

PD - useless for now
Grinder - obvious.
Synthesizer - used for adding elements to items.

[SaiKo]

Photon Drop: Dunno what it'll be used for yet. But said to be something of value.
Grinder: For grinding weapons/units.
Synthesizer: For buffing elemental attributes of weapons.

[ashley50]

Photon Drop ( no use atm)
Grinder (for strengthening weapons and units)
and Synthesizer ( for transferring abilities and strengthening weapon elemental attribute).

[Kimil Adrayne]

Welp, I think you got your answers

[Geistritter]

There are also Photon Crystals, by the way, five star items that look like bigger Photon Drops. Their extreme rarity suggests you'll want to hang onto them, although again, they're useless for now, because we just had to make some of PSU's abundant mistakes.

[HUnewearl_Meira]

Thanks, everyone. That's been bugging me for a while.

[GoldenFalcon]

There are also Photon Crystals, by the way, five star items that look like bigger Photon Drops. Their extreme rarity suggests you'll want to hang onto them, although again, they're useless for now, because we just had to make some of PSU's abundant mistakes.

There are also Photon Spheres. I believe that Photon Crystals and Spheres only pop out during drilling codes

[Geistritter]

That could be, yeah; I never noticed when I got Crystals other than from cashing in rewards at the Title counter.