this one with the wavy top rim appears to have had a stopper - my guess is that, decoration aside, its use may well have been for a liquid condiment i.e. an oil of some type - the body has that slender look.
As a reflection, I have seen pressed pieces where there has been an imitation concave pontil area - and just to be on the safe side it may prove useful to look more closely with a magnifying lens - to look for feint marks left by the grinding wheel.