Answer:
A single syllable do I claim black was my most famous name; Fetal to mortals here below thousands have I slain in a single blow.
I am a precious stone, as clear as a diamond. Though you can walk on water with my power, try to keep me, and I'll vanish in an hour. What am I?
I welcome the day with a show of light. I steathily came here in the night. I bathe the earthy stuff at dawn but by noon, I'm gone. What am I?
One simple click, one simple flash. A piece of memory, for years I'll last. What am I?
They are many and one, they wave and they drum, used to cover a stare, they go with you everywhere.
Those with eyes bigger than their stomach will definitely leave the restaurant with one of them. It is named after a house pet as well.