Unrefrigerated eggs should never be allowed to develop into embryos because they can become contaminated with harmful bacteria and pose health risks. Eggs that are not collected for consumption should be removed from the nesting area regularly to avoid the possibility of hatching.
If you are referring to fertilized eggs that you intend to hatch, the viability of the eggs largely depends on the species of the egg-laying animal and the conditions in which they are stored. Most fertilized bird eggs, for example, will not develop into embryos if they are not incubated within a certain period of time. This period can vary between species, but in general, it is best to incubate the eggs within a few days of being laid.
If you have fertilized eggs and are interested in hatching them, it's essential to research the specific species you are dealing with and understand their requirements for successful incubation. Maintaining proper storage conditions, such as consistent temperature and humidity levels, is critical for the eggs' viability during the incubation process. In any case, never attempt to hatch eggs that have been left unrefrigerated for an extended period as they are likely to be non-viable or contaminated with harmful bacteria.