I am sure that no one will be surprised that I totally disagree with MattMarriot on his conclusions, but I was curious about the skull and crossbones
that he mentioned. So, I did some searching and I did find this information on the burial of past Popes on this site
Macon Telegraph
Monsignor Anthony Sherman said
The pope's body will be interred in three coffins, one of cypress, which symbolizes humility, one of zinc or lead, to preserve the body, and one of
elm, one of the most expensive woods in Italy, conveying respect.
The lead and elm coffins will probably bear bronze plates with the pope's Latin name, Ioannes Pavlas II, and the dates of his life. The lead coffin,
which weighs 800 pounds, has traditionally been marked with a skull and crossbones
It might have been less confusing if Matt had used a different link as the wikipedia one didin't mention the skull and cross bones.
I also looked up the meaning of skull and cross bones on tombstones and apparently the Skull signifies the transitory nature of earthly life,
penitence, and mortality, and the skull and crossbones reflects death, crucifixion.
So as I said while I absolutely don't agree with his conclusions I found some information to support the
possibility that there was a skull
and crossbones on one of the caskets. Nothing I read specifically said that Pope John Paul had them on his casket but past Popes did