Something I saw in a store. These are large combination pans. Separately, comals are defined as griddles, and concas are bowls. Together they are a griddle bowl. There are two kinds, either with convex or concave concas (like an upside down or right side up bowl). Tortillas would be cooked on or in the conca, while the ingredients to go inside the tortillas would be fried on the comal ring around it. Typically, these are large pans, 16 or 22 inches in diameter, and used on outdoor gas burner stands, which have a ring the pans fit into, although the concave ones are flat on the bottom, which is small enough in diameter to sit on a hot plate, so I think those are more versatile.
By the way, I looked at the larger 22" one today, it has a higher outer lip around the comal (griddle), which is at least twice as high as the 16" pan. The conca (bowl) is larger too of course. I figured it would be for larger tortillas, but I guess the rim accomodates larger ingredients, or a higher pile of them too. Yeah, I like putting whole ears of corn in my burritos… not only that, but it looks like people use “tamale steamers” with the same sort of bases as these pans. You learn something new everyday.