Is there any animal who lays a green egg?

Yes, some bird species lay green eggs. The most well-known is the common loon (Gavia immer), whose eggs range from pale light blue to dark olive-green with reddish-brown splotches. Other bird species that lay green eggs include the emperor penguin (Aptenodytes forsteri), the marbled murrelet (Brachyramphus marmoratus), and the green jay (Cyanocorax yncas).