Viral eukaryogenesis refers to the notion that eukaryotic life (distinct from prokaryotes) arose as a result of some viral behavior. While elegant and interesting, little evidence has been found to support or deny this theory. Recently, UCSB Researchers working with bacteriophages observed that, when their bacteria host were close to death, the phages assembled a nucleus-like compartment to serve as the center of viral replication.
Scientists first attached fluorescent tags to bacterial proteins of import in the viral life cycle, and recorded those bacteria over the course of viral infection. This recording showed some tagged proteins enveloping viral nucleic acids to form a 'zombie cell' similar in appearance to a basic eukaryotic cell.
These results have been described as potentially "pivotal" for our understanding of evolution and the emergence of complex life. I feel that more research could be valuable with regards to determining where else this type of behavior may exist in nature and explore how these may elucidate new links between previously unlinked biological factors.
Chaikeeratisak, Vorrapon, et al. "Assembly of a nucleus-like structure during viral replication in bacteria." Science 355.6321 (2017): 194-197.