This is a relic
Catacombe di Roma standing crucifix cross with a possible fiber relic (photo #8) from the catacombs of Rome. I have looked under bright light with a magnifier and this could be a fiber, or just dust. I do not see any soil.
It appears to be silver plated with wear.
The front, base says Ricordo di Roma.
Around the back relic window is Catacombe di Roma, with MOD.DEP. at the back base.
On the four parts of the base are different buildings, churches I resume.
Please study the photos carefully as I try to picture the item accurately.