Looks like a sad iron holder. I remember in our family's homes where there was a cook stove that the women had the iron part on the heat to warm up, then used a holder to pick one up and use it while another heated. The iron part is missing in this picture. The spring form inside the holder caught and released the iron part and the ridge was for ironing close to a part of the garment.
That would be my idea.
Carol J.