An example of an analogy used in popular science writing:
"Lithium is the penicillin story of mental health. It was the first effective medication discovered for the treatment of a mental illness, and it is, without doubt, Australia's greatest mental health story."
de Moore, G., & Westmore, A. (2016). Finding Sanity. John Cade, lithium and the taming of bipolar disorder. Allen & Unwin.
This might be considered an implicit analogy as it is assumed the reader already appreciates the importance of penicillin (in treating diseases due to bacterial infection) or deduces it from what is written about lithium.
Note: the reference to lithium refers to the element (in compounds, as ions) and not the substance (the metal).
Read examples of scientific analogies