Sunken Journal from Duke, a Mystery of the Shrine of Flooded Embrace.
These seemingly harmless gems have a much darker side... The Sea Queen used them to imprison those from the world above. She bound their souls inside Mermaid Statues and the power of the gems transformed them into something else. She called these new creatures Ocean Crawlers and they were her army, a way to take the fight to the land dwellers. As well as corrupting and changing the poor souls inside, this process corrupted the gems too. These corrupted gems became known as Siren Gems.