Is this a siraui?

[kai]

Hello Ian,

I agree that there appear to be a couple of concentric rings around my example also.

Yes, the hilt of your example obviously includes the central part of a horn.

I'm less convinced that the opening really follows the growth rings - it does look a bit unregular/polygonal (anyway, waterbuffalo horn is not perfectly round to begin with) and, more importantly, several rings seem to (partly) touch the opening which might point to human intervention/carving.

Regards,
Kai