Here’s almost everything the Ante Nicene Father had to say on the subject of the shape of the earth:

The Flammarion (colourized 1)

The world, being made spherical, is confined within the circles of heaven.
Athenagoras (c. 175, E), 2.132.

Without a doubt, the world is beautiful. It excels as well in its magnitude as in the arrangement of its parts—both those in the oblique circle and those about the north, and also in its spherical form. Yet we must not worship the world, but rather its Artificer.
Athenagoras (c. 175, E), 2.136.

There was a time when the whole globe underwent change, because it was over- run by all waters. . . . Even now, her shape undergoes local changes.
Tertullian (c. 200, W), 4.6.

Let us first lay bare . . . the theory of the Chaldeans and the Egyptians. They say that the circumference of the universe is likened to the turnings of a well-rounded globe, the earth being a central point. They say that since its outline is spherical, . . . the earth should be the center of the universe, around which the heaven is whirling. . . . They say that surely the earth originally consisted in a state of chaos and disorganization.
Methodius (c. 290, E), 6.340.

The philosophers fancied that the universe is round like a ball. They also thought that heaven revolves in accordance with the motion of the heavenly bodies. . . . For that reason, they constructed brass globes, as though after the figure of the universe. They engraved upon them certain monstrous images that they said were constellations. . . . But if this were so, the earth itself must be like a globe. . . .
However, if you ask those who defend these marvelous fictions why everything does not fall into that lower part of the heavens, they reply that such is the nature of things. They say that heavenly bodies are carried to the middle and that they are all joined together towards the middle, just like spokes in a wheel. . . . I am at a loss as to what to say concerning those who, once they have erred, continue in their folly, defending one vain thing by another vain thing.
Lactantius (c. 304–313, W), 7.94, 95.

In the first place, indeed, the world itself is neither right nor left. It has neither upper nor lower regions, nor front nor back. For whatever is round and bounded on every side by the circumference of a solid sphere, has no beginning or end….
Accordingly, when we speak of the right or the left side, we are not referring to any- thing in the world, which is everywhere very much the same. Rather, we refer to our own place and position.
Arnobius (c. 305, E), 6.477.