1.) Behind Bendezium wall. Use X-Ray to reveal; blast with Power Bombs :: Chozo Ruins, Magma Pool
2.) Hidden under sheet of ice on rooftop in corner across from Chozo Lore; use Plasma Beam :: Phendrana Drifts, Ice Ruins West
3.) Use Grapple Beam to arrive at the highest point in Phendrana's Edge :: Phendrana Drifts, Security Cave