Eggs are an interesting and slightly more complicated case for food taxonomy. Most of the time by “egg” we mean chicken egg, or more precisely “hen egg food product“. But eggs from other birds, fish, turtles etc. can be consumed.
Currently in FoodOn an egg is considered a developmental form of an existing “vertebrate (animal) food source” organism, and so is not listed separately there. Various kinds of avian and reptile eggs are (or will be) listed under the “foodon product type > vertebrate animal food product > egg food product” category [FOODON_00001274], which encompasses fish, bird, reptile etc. eggs.
FoodOn has a separate “part of plant or animal > part of animal > egg or egg part” class [FOODON_03420194] that provides a vocabulary for food processing based on an egg’s anatomical parts – its UBERON anatomy egg components like albumen [UBERON_0008944], egg yolk [UBERON_0007378], or eggshell [UBERON_0005079]) and is agnostic about what kind of animal the egg is from.
Note that egg food products can be distinguished by having a “shell off” or “shell on” in product name, e.g. “egg (shell off, dried)”. We include UBERON “shelled egg” which is defined as an egg with its shell on (but note this diverges from common use of english where this often implies having the shell removed). FoodOn’s “egg (without shell)” is also included.