I work at a Zoo and a co-worker gave me 4 duck eggs found in a flower bed. We have Mallards, Muscovy, and white duck pairs who roam around and beg for bread so no telling what the parents are. I candled them when I brought them home and didn't see any development, sat them on the 17th. Candled them today and there are veins so now any idea about how long before they hatch? I do understand there are differences depending on the breed, correct? The eggs have a slight green cast to them.