We’ve seen it many, many times: the ship gets into a firefight, takes a few hits, shakes around, and consoles explode (possibly taking an unfortunate ensign with them). Eventually the battle is resolved with our heroes largely intact if somewhat shaken up. If it was a particularly nasty battle, there will be signs of damage: scorches on the walls, deformed equipment, busted lights, and rocks scattered about.
All of that seems reasonable… except the rocks, which look pretty out of place in a spiffy 24th century starship. So why are they there?
My understanding is that the “rocks” are a product of the electroplasma system being exposed to air. Whether that is some sort of coolant that is meant to seal the EPS leak in that console or some sort of EPS byproduct reacting in air, I don’t remember or have a head-canon for it.
All of that said, if I form this reply into one worthy of Daystrom, then I say it is an intended safety mechanism to protect the crew against catastrophic failure of the EPS conduits.