I think I do see the pattern being 'pressed inward', but what I can't see is the tempering material. Usually in NA pottery there's some obvious material mixed in w/ the clay- so it would fire well- without exploding. Sand, crushed shell are 2 examples of what gets tossed in the mix, so you need to look for that- and any places on the piece where it is not perfect- any edge or surface. That's where the evidence of the tempering material will be most obvious. See what you see and try to get a good sharp photo of it- or a couple. If it's too smooth and uniform, it may well be modern- like an old flower pot or terra cotta vase, etc. Yakker