An example of simile in popular science writing:
"Other regions of junk DNA are genetic interlopers, derived from the genomes of viruses and other microorganisms that have integrated into human chromosomes, like genetic sleeper agents. These remnants of long-dead organisms carry potential dangers to the cell, the individual and sometimes even to wider populations."
Nessa Carey (2015) Junk DNA. A journey through the dark matter of the genome. London: Icon Books Ltd.
'Interloper' can be seen as a metaphor (actual interlopers are surely acting deliberately) as the reader is told the regions of DNA 'are genetic interlopers', but the 'sleeper agent' reference is marked as a figure of speech.
Read about examples of science similes
