Neutrinos are minute elementary particles that were only directly detected in 1956, five years prior to the publication of
Solaris, though their existence was theorized decades earlier. By suggesting that the ocean constructed the replicas out of neutrinos and calling the replicas’ cellular structure “camouflage,” Kelvin is insisting on the replicas’ radical alienness and inscrutability despite their surface-level indistinguishability from human beings.