Hi, Just noticed when playing the campaign, there is a plasma grenade embedded in stone on the Swords of Sanghelios mission next to some intel. When you shoot the plasma grenade there is swooshing noise. Do you know what this is for, I suspect there are other grenades hidden on the mission to shoot !? Here is a link to the video on my you tube:- Halo5 - Sword of Sanghelios - What is this? - YouTube Any ideas, thanks EVSY.
Now I gotta check this.
That’s really interesting, I wonder if its part of a larger easter egg? I’m on my legendary playthrough I’ll have to check it out!
Cool - let me know what you find 
I will keep looking too. keep you posted 
Nice find! Thanks!!
It just looks like a normal plasma grenade, that you couldn’t pick up (because you already had 2), and it just blew up when shot. I may be wrong, but it doesnt look like anything special.
Other then that, maybe idk what you’re looking at, and I’m looking at the wrong thing lol.
Must be an easter egg. There is a similar one on Blue Team, where you shoot an elite skull, and sparks come out. There is a second part to the Blue Team easter egg that no-one has found yet.