The WT doesn't believe in a literal plain reading of Genesis. True to form, when something doesn't fit their narrative, they simply wave it away and say this must be symbolic. Once you understand their grift, you start seeing it in all their writings.
They believe in billions of years and progressive creation. They teach this, even though virtually every Hebrew scholar in the world agrees that the language and context of the creative days in Genesis were meant to be understood as literal 24 hr. days. Ex. - "there was an evening and a morning, the first day".
Like most anything the WT touches, they get it wrong. You have successfully refuted the false WT teaching of "Progressive Creation", but not 'Biblical Creation'.
The fossil you referenced does represent rapid burial in a catastrophic event. Biblical Creationists would say this evidence is consistent with a catastrophe like the biblical Noah's flood.
Clams all over the world are found fossilized, tightly together in the "closed position" like the one pictured above. Normally when a clam dies, it opens up and the shells are found in halves.
Another example of rapid burial.
After abandoning the false narrative of progressive creation, next stop is abandoning the WT false teaching of "billions of years".
Here's a good place to start. List of 'Not So Old Things'.
