Peter Watts does proper hard sf. Sometimes, at the cost of good storytelling (Echopraxia) but sometimes it is just glorious (Blindsight). This was a curiosity of a novella. A story of deep time, with a fascinating and original premise and even a link to a hidden story within the text. I really tore through this as I found it pretty gripping and intriguing. It is part of a wider series of stories (Sundowner) but I had not read any of the others and found this still stood alone fine. Recommended.