On Dec 21, 8:12*pm, scott wrote:
Wondering what this is and what (if anything) I need to do? Anything to worry about? Location: backyard patio, desert landscaping, Las Vegas area. Thank you.

Picture of spot-- *http://imgur.com/aw252

You might have a look at this too.
http://en.wikipedia.org/wiki/Reinfor...orced_concrete