8 egg cups or snail cups in flamed stoneware

Set of 8 small stoneware bowls with a pretty flamed enamel in gray and brown tones. I always took these cups for egg cups but I was told that they could also be snail cups! But in terms of size, they are perfect for enjoying a good boiled egg with its buttered and browned fingers in the oven, yum yum! They are obviously all a little different, on one you can even see, it seems to me, the imprint of the enameler! They probably date from the 70s. They are not stamped, but I would lean toward a production from the niderviller earthenware factory. I spent my youth a few kilometers from this earthenware factory and I remember egg cups with this rather particular shape in family cupboards. They are in very good condition, no cracks or chips, just a slight lack of enamel, therefore original, on a small area of one of the egg cups. They measure 4.8cm in outer diameter, 4cm in inner diameter and 3.7cm in height.