When dropping 3 items in one go on the ground, if one of them has a glowrune, it leaves a glowing orb on the ground. This orb is similar to that of the runed item, but persists even after the pile has been picked up.
sometimes 2 orbs appear on the tile: one random and the other where the pile was
They do dissapear after a relog.
hallway filled with orbs:
https://prnt.sc/tumphl
orb+pile: https://prnt.sc/tun1mo
2 orbs https://prnt.sc/tun1tq