Quick question for the Historians in the Room

[Fragony]

Don't know the symbol but it looks like normal grafity. In excavations in Pompei they found loads of it, often hilarious 'he/she sucks for this and that'. Probably indeed the chalice, symbol looks to be more recent then the text below it. Looks like something else was there, look closely behind symbole something used to be written there, looks like a religious paintjob to me