Tosefta for Chullin 127:5

And as to eggs, any [egg] that narrows [at the top] and is rounded, if it is known to be from an impure bird, and any [egg] that does not narrow [at the top] or is not rounded, if it is known to be from a clean bird, is clean (see Hul. 64a:2). They may take eggs from either of them and they need not be concerned lest [the eggs] are from carrion or from tereifot. They may not sell eggs from carrion or from teriefot to idolaters unless they are cracked open into a dish, and moreover, [the Sages] said, they may not buy from idolaters eggs cracked open into a dish.