Sycorax is a witch from Algiers and the late mother to Caliban. She arrived on this island in a similar fashion as Prospero – abandoned, and with a child. Sycorax was pregnant with Caliban when she came ashore. She died many years later, after which time, Prospero took in the orphan Caliban as his own.
While Sycorax does not appear in The Tempest, her unseen presence casts a dark shadow over it.
Use the cipher in Caliban's cave to decode the message on her grave.