~~~ badly decomposing and recored/noted as being so for the past 25+ years; mostly due to improper storage and moisture problems... Unless you have a scan of the original offer showing the piece w/o the stress fractures there is very little you can do other than to alert the seller. Some of those plaques simply break into pieces if only lightly dropped onto a hard surface (table/desktop).

We've actually seen burlap sacks of that series in Southern California completely damaged with only a few being saved; and we've also seen material coming from the UK (of that series as well as others) in the same condition... yet the pieces continue coming to market with results as your example when reaching their destination.