When we were down there in the darkness, by the light of our flashlights this seemed to look like a mighty eagle. In the photo it seems to me to appear more like an odd pinguin-dog hybrid!
Jeong-Ah discovered that if she shined her light directly into some of the travertine it gave off this ghostly glow -- with different chunks giving different hues. More in the next two photos.
Jeong-Ah had made some delectable gimbap (sort of a Korean sushi -- Brad, please correct me with a comment below if I am wrong on the name) for a picnic after the spelunking.