Flukes

Look at all those spikes. Art from SS.

Lorn-Flukes are monstrous, possibly primordial creatures that appear to be giant sea urchins. They can easily overwhelm ships, both by physical destruction and terrifying the crew by speaking words of The Correspondence. Originally from the planet Axile, like their sometime servants the Rubbery Men, they are enemies of the Masters of the Bazaar and seek to control or destroy the Bazaar.

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

A few more interesting spoilery snippets
When killed, lorn-flukes leave behind a core which glows irrigo, the colour of forgetfulness, and is made of the souls of the creature's victims. It may be possible for individual humans to be transformed into Flukes as well.