While digging, I found a long tunnel that went straight down. I fell to the bottom, where it had a sword. I realized this was an enchanted sword shrine. I am pretty sure those are only on desktop, and I checked the Wikipedia. How did this end up on my Mobile World??
Terraria – How do Desktop Only items get into the Mobile world
terraria-mobile
Related Solutions
The game has a total of 21 NPCs that can move into your house. They are:
- The Guide
- The Merchant
- The Nurse
- The Painter
- The Dye Trader
- The Demolitionist
- The Dryad
- The Arms Dealer
- The Party Girl
- The Goblin Tinkerer
- The Witch Doctor
- The Clothier
- The Mechanic
- The Angler
- The Traveling Merchant
Additionally, in hardmode you gain:
- The Pirate
- The Truffle
- The Wizard
- The Steampunker
- The Cyborg
- The Tax Collector
Finally, there is one event NPC that do not live in housing:
- Santa Claus (shows up randomly between Dec 15-31st)
If you look at the wiki you can see a list of all the NPCs in the game. You can tell which NPC is only available in the PC version because these NPCs have a small icon of a computer directly after their description. It looks like this: 
According to the Terraria wiki, all maps in Terraria mobile are the same size as small worlds on PC. This is 4200 blocks wide by 1200 blocks tall.
Best Answer
Unless you got an Enchanted Sword from it (which is not possible), it wasn't an enchanted sword shrine, but just the generic "sword in stone" breakable object.