 Cuckoo bird does this. I'm just gonna run through it real fast. The cuckoo bird watches the warble bird, sits over here and watches. And the warble bird just works, builds a nest and works and builds a nest and lays its eggs in there and they go back to get more nesting material. And the cuckoo bird goes in, flips one of them out and in a few seconds lays their egg, lot bigger bird by the way, lays their egg inside that nest that looks just like those eggs.