Heaven by Ian Stewart and Jack Cohen.
This is a mind-blowing imagining of alien worlds and beings drawn from the new biology minds, machines, and social systems. It weaves the mimetics of religion, cybernetics, collective intelligence, quantum-mechanical entanglement, and the ecology of mind to create some of the most exotic yet plausible characters ever to be assembled in one story.
Consider, for example, a species of coral whose female sex is capable of conducting massively parallel computation on a planetary scale, and equally deadly biological warfare, while the males travel the seas and conduct commerce in upside down sail boats; a Borg-like meta-organism called Cosmic Unity whose missionaries are disseminating the Memeplex of Universal Tolerance throughout the galaxy; a species of telepathic feline Neanderthals; and you meet these in just the first few pages.
It is an exuberant romp through the many ways organisms, or collections of organisms can evolve or co-evolve to become sentient. It quickly becomes clear that sentience, intelligence and evolutionary fitness are quite different things and not necessarily related. What is adaptive in one environment or at one scale can be maladaptive in another. Cosmic Unity, for example is highly intelligent, and is fit insofar as it is taking over the galaxy, but it is dangerously maladaptive in initially unforseen ways.
If you are looking for something satisfyingly different, this is it.