Vintage Cake Pillars (Harrogate HG1)

Brand: 'Art for Eating'.
Bought in the 80s or 90s.
Made of plaster/gypsum, hand-finished with a marbleised colour wash (according to Google Gemini).
They are not washable.
The marks on the pillars are probably grease/oil stains absorbed into the porous plaster over time.
They shouldn't be used in contact with food but if they were to be used in a cake display, a food-safe layer, e.g. foil-covered cake board or a plastic separator disk) should be placed between the pillar surfaces and the cake itself.
Attractive vintage items which could be used in other ways, e.g. photo props, or they could be re-painted and/or sealed for craft projects.