Flukes

Lorn-Flukes are sea creatures that appear like giant sea urchins.

They can easily overwhelm ships, both by physical destruction and terrifying the crew by speaking words of The Correspondence.

They are enemies of The Masters of the Bazaar and seek to control or destroy the Bazaar.

They are originally from (to be filled in, can't remember)

There is a captive Lorn-Fluke in the Cave of the Nadir in The Forgotten Quarter.

What are Lorn-Flukes, really?
When killed, they leave behind a core which glows irrigo, the colour of forgetfulness, and is made of the souls of its victims. It may be possible for individual humans to be transformed into Flukes as well.