Are you sure it isn't describing the physicality, though?
As I was saying, for something to be a metaphor, it has to actually convey some knowledge about domain A to domain B. Otherwise saying A when you mean B it's not a metaphor, it's just muddying it and being crap at communicating.
As a metaphor for the formation of a round world, the clay seal metaphor is useless. It doesn't convey any actual information. All the known aspects of making a clay seal are all wrong for describing how Earth was formed. (Like most creation references, in fact.) Not only it's not flat, but was not made of mud and dried. It was not stamped or modelled with a mold, but it's a combination of own gravity and plate tectonics. Indeed if you did mould a shape into earth to any recognizable size, it would just be crushed back into a round shape by gravity. It doesn't even have the same kind of relief as a clay seal: if you made an accurate scale model of the Earth the size of a billiard ball, it would actually be smoother than a billiard ball. (Yeah, even the Everest doesn't do much on a 6,371.0 km sphere.) So, you know, it's nothing like a clay seal.
I'm not saying God meant any of those, but, really, I'm drawing blanks as to what information is he trying to illustrate for the Earth, by using a clay seal to illustrate it. Any detail, no matter how relevant or irrelevant, is just wrong for it to be a metaphor. It's not actually conveying any useful information at all, but at best just misleads.
So, you know, either it's not meant as a metaphor... or God is a moron who can't communicate. Just about every single of his metaphors or (especially in the NT) parables, just muddy the topic, AND use more space than just saying what he means, AND tend to create some rather unfortunate implications that draw attention from the actual topic.
And, seriously, if you look at known theology across history, practically any two theologians understood two different things from them. (Three, if they were rabbis

) By now the body of conflicting interpretations of those "metaphors" is vastly greater than the actual text, and that's not even counting the midrash.
Frankly, it seems that the only way to find it a metaphor for how the earth was formed (or for morals, or whatever) is to already know what you must pretend to get from it. If you don't already know, say, that reptiles came before birds, or that complex plants with fruits and seeds came LONG after there was a visible sun, Genesis isn't going to illuminate you through metaphors, but give you all the wrong ideas.
Either that wasn't supposed to be a metaphor for anything, or, really, God is crap at communicating anything. And either of those doesn't exactly inspire confidence in getting any wisdom from him.
In fact, it's more like Bill Engval should give God a "here's your sign" so people know not to ask him anything
