There are two kinds of Flatlanders. And no reason they can't share the same planet. They just have to wear environmental suits to visit one another.
[ID: An MS Paint drawing showing two 2D people, both in the shape of squares. They are staring at each other and sharing a dialogue box that reads, "What an impossible creature!". One of them has four legs and arms, four whiskers on the top of his head, one of which is reaching out to the other square. He has two eyes, one on either side of his body. He stands on the ground. The other is a square that has no limbs, and is wearing a simple fitted environmental suit with a bubble around his single eye, with a rope leading upward off screen. Both of them are drawn as they appear from above, with their internal organs visible. Both are purple on the inside, with different blogs in shades of pink, purple, and red for their organs. Text under the ground reads, "An expedition to the dense southern core led to a surprise first contact with Flatlanders who evolved to fill a very different niche..." Next to this is a small circle with a stick figure on it, inside a larger circle. An arrow points at the smaller circle, labeling it, "U R here". End ID.]
