Invisible Ether
Sentience is defined as a state of awareness of one's own existence. For most of history, humanity believed we were the lone species to enjoy true consciousness. We were wrong.
It wasn't surprising when we learned apes, dolphins, elephants, and other higher mammals were definitely sentient. We'd always understood they were capable of a full range of emotions. But when scientists concluded that the dust mites were also conscious beings, people began to freak out.
It's weird to think about the billions of tiny souls floating in the invisible ether.
In a total non-surprise, the fundamentalists are calling them angels.