Just checked in AJTT.
It's a 10 L15p movement, the second movement produced by Omega and it does not display a serial no. The description is that it is a "ladies calibre" first produced in 1897. As far as I can make out, it was used in ladies pocket watches.
Wristwatches were produced shortly after 1897, but they didn't use the modern lugs seen on this case. So, I deduce that it is a legit and possibly rare movement housed in a later case.
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