How to create a Sci Fi antagonist in fantasy RPG?

I really enjoyed the replicators of Stargate and I want to include them as long-term enemies in my created adventures. My challenge: I am playing The Dark Eye, which is a fantasy setting RPG.
How do I magically explain their skills for replication?

How can I make them ‘flavorful’? Maybe instead of robotic bugs they’re magically created and ‘sand bugs’? Is there a “best practices” for porting Sci Fi creatures like that into The Dark Eye?