Help!  Does anyone know what an "olive" is?

The Shelburne Museum is restoring the steamboat Ticonderoga.

We have found the original 1906 order to outfit the boat including the
following items to supply each corner sink area - a bowl, a comfort
(chamber pot?), spoonholder, water pitcher, a towel, towel hardware, a
cuspidor and an olive.  The term olive doesn't appear in hardware or
Sears catalogues of the period that I have looked at.

The mysterious olive cost $.85 in 1906.

Any suggestions would be most appreciated. Many thanks, in advance, for
pondering this weighty question!