I have the same tetradrachm of Nero as yours :23,5 mm , 12,98 gr , as 12 uur .
The reverse is the personification of the town Alexandria.
In the first century of Roman art, a woman with an elephants symbol was the image of Africa. The first representation of a head with an'exuviae elephantis' is on a tetrdrachm of Ptolemaios I, about 320/315. The represented person is Alexander the Great. Ptolemaios made also an analogy of Alexander with Heracles with a lions skin, referring to the battle of Alexander with Poros on an elephant in Hydaspes in 326 BC.
In the Julian-Claudian period is there only one representation of a woman with a cap in the form of an elephants head, this coin, the reason why numismatics think it is a representation of Alexandria.
The personification of Africa occurs not often in the period Traianus-Hadrianus and Africa is also represented as an elephant or a protome .
I am making an inventory of my coins for my daughter and this is the commentary I made for this coin.