What's the Name of That Book??? discussion

I briefly read the back of this book in a Barnes and Noble in Layton Utah in 2018. It's about a civilisation of people who can only move in one dimension, and they get a helper worm thing implanted to help them move in another. I remember one part where I think someone close to the main character rips her ear worm out for some reason, and it's dangerous.
It's a nomadic life, they follow the light of their planet in order to survive.
I think the cover was dark, green or black and gray, possibly with a planet depicted on it? It wasnt a big book, either, maybe a thin paperback.

Greg Egan's The Dichronauts Dichronauts

"Seth is a surveyor, along with his friend Theo, a leech-like creature running through his skull who tells Seth what lies to his left and right. Theo, in turn, relies on Seth for mobility, and for ordinary vision looking forwards and backwards. Like everyone else in their world, they are symbionts, depending on each other to survive."