YUCK!

The pattern on this faucet is so cool...but I had no idea what was "lurking" under there. Lime scale is it? My kids drink out of these faucets! I proceeded to look at all my faucets (by macro camera) to discover they all have different patterns, but similar crud. Maybe this is the end of my macro guessing games? 

Anyway, Mom's guess was close enough. Mom Wins!