Reverting Transmogrification
Placing a transmogrified item without an appearance item in the Transmogrification Table will allow you to remove the transmogrification entirely.
Hiding An Item
Transmogrifying an item with a Void Fragment will make the item not show up on the character or in their hand!
Transmogrifying a Sword
Showing off transmogrification of a Netherite Sword!
Eating Dirt?!
This is actually an Enchanted Golden Apple which has been transmogrified to look like dirt, but there's absolutely no way to tell!