A series of short stories, generally centered on alien life existing in particularly weird environments or otherwise extremely strange from human perspective. After each, there's a short essay discussing the science behind the story and whether life like that might really be possible.
It's certainly a cool idea for an anthology (and apparently another, longer one with a similar concept was just recently successfully Kickstarted), and the stories are mostly interesting. One, "The Island" by Peter Watts, I'd already read (and enjoyed) a couple times before but the rest were new to me.
Two of the stories didn't really go with the premise. At least one was completely human based and looked at SETI, which I could sort of see as being tangentially connected, and yet it's not really a story about the strangeness of alien life and so it felt a bit disappointing after a few of the other cool stories... not just for that, it didn't really feel that good, like the premise (ending included) was meant as a the kind of joke you might smile at, or the twist of a forgettable Outer Limit episode rather than a believable story of how a situation like this might go down. The another, "But Still, I Smile" by D. A. Xiaolin Spires sort of deal with a strange alien species and yet felt like a jarring inclusion because the others felt like at least an attempt to portray an alien life with some amount of scientific rigor--a variety of hard SF, in other words, whereas that one felt like just a random 'wouldn't it be cool?' idea that worked more as a metaphor than an actual encounter? Nothing particularly wrong with that, but didn't feel like it fit in with the book, and wasn't to my tastes otherwise.
There were only eight stories in total, and, leaving out "The Island", I can't think of one that particularly jumped out at me as best. Probably between “War, Ice, Egg, Universe” by G. David Nordley which had a cool alien mindset that was fun to try and wrap my brain around, and "A Jar of Goodwill" by Tobias S. Buckell.
The collection was offered for free, so certainly worth a look. I'd say probably in the 3-3.5 stars range on its own but bumping it up to 4 for that alone (or rather, bumping it up to somewhere above 3.5 which would then round up to 4).