Crystallized Echo of the First Song
Can be found near waterfalls in the Sepulcher of the First Ones area.
You will see a musical notes effect and hear faint musical sounds playing from it (likely Song Notes).
They require Protoform Synthesis (Mount) in order for the object to show up for you (you will still see and hear the musical notes).
Known locations:
/way 77.6 59.0, inside a cave
/way 78.2 54.4
/way 77.6 60.4
/way 77.4 45.3
/way 78.3 53.1, under the platform, but reachable from /way 78.4 52.9
Not the raid island-
/way 58.6 89.9, at the top of the waterfall coming out of the distant progenitor forge (orb) (under water)
None the Wiser Guild 