Writing Down the Bones is a book of something like zen koans combined with writing prompts. The chapters are never more than 4 short pages (the book is physically small), and are designed to get you to sit down and write after you read each one.
It was not super-useful to me, honestly. I’m not often in a space (physical or mental) where I can switch between reading and writing like that. I did try to just sit down and read it, but the chapters were too short and pithy to flow well.
I’m sure Writing Down the Bones works for some folks. It wasn’t for me.