Egg

Egg is a creature type used for cards that depict the developing embryo stage of a bird, reptile, fish or invertebrate as an oval or round object with a chalky shell or leathery membrane. When used on creature cards they regularly turn into another creature type when a certain condition is met. When eggs are depicted on artifact cards this is not always the case.

History
The first card to use the subtype was Rukh Egg from Arabian Nights, followed by by Chicken Egg from Unglued. Meanwhile artifact cards like, or  always lacked subtypes.

When the colorshifted card Roc Egg was printed in Magic 2011, the creature type "Egg" was decommissioned and Rukh Egg was changed accordingly. As explained by Mark Gottlieb, Rukh Egg and Roc Egg were, essentially, very (very) young Birds, so they both received that creature type. Summoner's Egg was granted the creature type Egg during the Grand Creature Type Update, but it was never printed like that. With the Magic 2011 update it became a Construct. The Unglued Chicken Egg was never changed, because un-types are not mentioned in the comprehensive rules.

Similar to Roc Egg, Dragon Egg was printed as a Dragon when it first appeared in Magic 2014. However, the Egg subtype was reinstated when that card was reprinted in Core Set 2019, now with the subtypes Dragon Egg. In this way, Egg now can be defined more as a class than as a race. With the Core Set 2019 rules update the type was also (re)added to Rukh Egg, Roc Egg, Summoner's Egg</c> and Ludevic's Test Subject</c>.

Trivia

 * As an April Fool's joke in 2002, Rei Nakazawa announced the creation of the "Vitellines" for Onslaught. These were supposed to be rotten, greedy, and vicious egg-like creatures which would invade Otaria and overthrow the Cabal. Formed from red and green magic, they were said to have developed their unique egg-like shape from the massive heat and pressure that existed in the volcanic heart of the Shivan mountains.
 * Commander 2019 introduced an Egg Tribal Commander with Atla Palani, Nest Tender</c>.