Geometric white clay pottery vase

This vase is 13" high x 9" wide x 6.5" deep. Thrift shop find from today. I am a color and shape junkie so I honed in on this vase. At first glance, I thought it was probably just some cheap Chinese decorator item, but then I saw the "X" under the glaze. It looks like maybe a second, to me. There are no other marks on it. The interior is also glazed, the mouth and neck in yellow but the body is white. Pottery is not my thing, but I wondered what importer would be happy seeing something like this on their loading dock? This made me think it must be American and it should be easy to find another one like it on on ebay, Google Images, etc., but of course not. I then wondered if it might be someone's pottery class project, but it seems a bit complicated for that and doesn't explain the "X". Now I have no idea what I have here. I thought maybe one of the pottery experts on CW could help me out. (Help!)