I am trying to identify a Greek glyph found in an ancient Latin text. I have
not seen what it looks like, but it has been described to me as an "8" with
the top circle opened.

The sign was in a word looking like "8???" ("8rôn") and which, according to
the text, corresponds to Latin "urina". If I understand correctly, the text
also says that this sign is a diphthong which in Doric was substituted by a
plain "?" (omega): "Nam olem a Graecis per <8> diphthongum scribebatur, quae
Dorice in ? solet commutari".

Therefore, I tentatively identified the word as "?????" ("ôurôn"), and the
unknown glyph ligature as an "??" ligature ("ôu": omegha + upsilon).

Does anyone know whether such a ligature actually existed in old typography?
And was it anything like an open "8"?

Thanks in advance for any info.

_ Marco