When Edessa reverted to paganism after Abgar’s death, the shroud was hidden in the city wall. Most likely this was stored in a jar.
After Abgar’s death in AD 50 his son Ma’nu V became king. However, the latter died soon afterward
and his brother or son Ma’nu VI came to the throne in 57. He reverted to paganism, persecuted
Christians, and sought to destroy all of the associated relics. Therefore, Edessa became hostile to
Christianity until the rule of King Lucius Abgar VIII 120 years later. The Shroud and the Keramion
were hidden within the city walls by church officials and forgotten for over 460 years.
https://www.researchgate.net/publicatio … Holy_Grail
The Dead Sea Scrolls were found in special jars. These jars were various sizes and were long and narrow with a lid.
The Dead Sea Scrolls, or Qumran Caves Scrolls, are parchment and papyrus scrolls that were found rolled-up inside special jars with tight-fitting covers, which helped preserve them. The jars were locally made in the Dead Sea area.
https://www.worldhistory.org/image/8468 … olls-jars/
It is theorized the large water stains on the shroud is a result of being in a narrow jar such as the Qumran jars.
The theory of a safekeeping of the Shroud in a slightly curved slanted near vertical position,
incited us to try and find what kind of receptacle could have been used to store the Shroud in
this way. We had reasons to believe that it could have been an ancient earthenware jar like
those produced in quantity during antiquity.
https://www.shroud.com/pdfs/aldo3.pdf
The large water stains on the shroud support it was folded and placed into a long narrow jar and water at some point entered the jar.
https://debatingchristianity.com/forum/viewtopic.php?p=1123238#p1123238