This is the pointed base of an amphora or wine jar which unusually has the maker’s name and a date scratched into it : NI. ATICI and the date is XVII K I
The explanatory museum label explains that the last ‘I’ is the first letter of the month – so January, June or July since there is no ‘J’ in the Roman alphabet. Then it says the date is 16th of December, May or June. Confused? The Roman numerals XVII are the number 17 so why the 16th day of the month?
While today we count our days forward from the start of the month the Romans counted backwards – from the first day of the next month! The first day of the month was called Kalendae or Kalends – or just K for short. So the date on our amphora is counting backwards from the 1st of January, June or July. In a month with 31 days that would make XVII K = what we would call the 16th day of the month before!!
(See Amphora Handle for more general information about amphorae.)