(Not a new topic but I just saw it…)
Apparently, when Don Bosco’s remains were unearthed in 1934, they were found to be incorrupt. At that time, they were displayed and many thousands viewed them.
After that viewing, his body was burried beneath the glass display where he had been viewed and what is now seen is actually a mold which contains a relic of the saint.
This is not a secret or some deception by the way. It is sometimes misunderstood, especially when one catches a glimpse on the web or views something without a tour guide or book to provide the details.
I’m no expert, just happened to do some reading recently.
Hope that helps.
God bless.