I'm new to Minecraft, and I decided to go on Creative and dig as deeply as I could. So I chose a spot near a mountain and started digging. It wasn't very long until I found myself in a deep underground cavern filled with what appeared to be glowing eyes or lights. I flew out of there as fast as my space bar would let me, but I still don't know what it is. Can anyone help me? Thank you.
Added (1). Just so you know, I'm terrified of the dark, both online and in real life. Any tactics for a scardey-cat trying to be brave enough to enter wherever this is on Creative?