The Phalgas's Eyelids are holes dotting the Knur Slagming plain. They vary in size, with the smallest 10' across and largest up to a half a mile in rough diameter. Geologists say that these holes are not natural and look to have been the product of tunneling by purple worms or other Underdark burrower. They are puzzled as why something would dig holes from the surface, and end over an Underdark sea. These holes go by a number of names, with Phalgas's Eyelids being the most used. The Githirmil have their own word for them - Gruumsh's Spittoons. The latter is the area's surface name.
In the Third Dragon Wake (1575 HE - 1576 HE), these massive hole served as the egress point for purple dragons. These creatures of the Underdark, driven by the Dragon Wake frenzy, flew up from the dark reaches of Imgangreth and raided the surface.