I'm not going to spoil anything, suffice to say that the object that is encountered in space is nothing like anything portrayed in science fiction before. The exploration narrative goes far beyond Clarke's Rama, and Watts poses some very interesting philosophical questions along the way.
The book has some minor narrative issues that annoyed me, but still a great read.
[1] https://www.amazon.com/Blindsight-Peter-Watts/dp/0765319640