These are rectilinear, though there are curved quarter cone sloped and their inversions. But yes, the first piece is a concave corner, so you can build with those 45° slopes retaining pools, skate parks and other basins. Convex corners let you make full skirts and hip-rooves. Inverted convex make good column tops. Inverted concave, hensteeth (I think they have been made, but they were in some dear set and putting them on pick a brick, nada. at last check).

Rounded concave and its inversion would be SWEET. So would a 2x2 base coming to a centered 1 stud. These exist as turret and rocket tops, but as more esoteric solids? IT WOULD BE EPIC! (hmm, you may forget I was a history major. Really.)