I met also that which had been her grandmother. For eighty thousand years Pth’thya-l’yi had lived in Y’ha-nthlei, and thither she had gone back after Obed Marsh was dead. Y’ha-nthlei was not destroyed when the upper-earth men shot death into the sea. It was hurt, but not destroyed. The Deep Ones could never be destroyed, even though the palaeogean magic of the forgotten Old Ones might sometimes check them.

The Shadow over Innsmouth Chapter 5