The Parasite

The visitor from the stars wanted to protect the caves, so he apparently put deadly parasites inside the cave walls to repel trespassers.  In "Rush," these parasites wreaked havoc on several citizens of Smallville, burrowing under their skin and releasing massive amounts of adrenaline.  Below is Chloe examining a glyph painted on the cave walls that warns of the parasite.

I'm not sure why the same symbol that appears on Naman's chest in the glyphs is on the parasite's head other than it's probably indicating that a) the parasite is from the same place as Naman's ancestors and b) Naman is immune to the parasites (and, indeed, the parasites cannot harm any Kryptonians since they wouldn't be able to pierce through their skin).  Here's a wider shot of the entire glyph and Kryptonian writing that accompanies it; the blue lighting is the flash from Chloe's camera.

The writing, when translated, reads: