This vintage kitchen tool is an egg separator, also called an egg-yolk separator.
A raw egg was cracked into the shallow metal cup. The rounded yolk remained in the centre while the egg white drained through the openings into a bowl below.
Before modern plastic separators became common, sturdy metal versions like this were useful for baking recipes that required yolks and whites to be prepared separately.
They were especially handy when making meringues, custards, sponge cakes, and other traditional desserts.
