It's a sarcophagus.

Knuckles knows from watching
horror movies that nothing good comes
from opening something that holds
someone's remains, much less if it comes
from an ancient civilization.

But before he could keep going, the icons
of the sarcophagus start to glow: first in orange
and then in light blue. All of the sudden, the cover
blows out and a blinding flash lets out a small
speck of orange light that goes towards a
terrified Knuckles.