Adam:
Sprinkler heads are man-made and should go for numerous reasons.
It's been years since I posted this ultimate hard-luck sprinkler head story so I'll post it again as it apropos here.
This involved a good friend of mine, Mark Shuman, who's part of that crowd at Philly CC, very much including Chet Walsh who are so mathematically crafty and coony it's almost like they have a permanent leaderboard complete with the cut line and leader scores implanted in their brains. I'm not kidding about that--year in and year out they're really amazingly accurate that way!
Anyway, Mark Shuman comes to the last hole at Wilmington CC in the US Amateur qualifier and he just KNOWS (which of course turned out to be absolutely correct) that he needs a par on that par 5 hole to qualify on the line (not the playoff line)!
He's standing out there in the fairway over his second shot after a great drive and he knows he can reach the green in two over a fronting pond with any one of his woods just hit relatively solid. But he thinks why take the risk, it's easier to just hit a simple layup, then a simple wedge on the green and still make perhaps birdie and certainly a safe par.
So he decides to lay up. The next question is with what? He calculates he can hit up to a good 7 iron and still come up short of the pond. Then he remembers Ben Hogan's adage that if you're gonna lay up make sure you really do lay up. So Mark starts thinking about an 8 iron but then he thinks what if I flush that or blade it a bit or something, so he decides on a 9 iron, takes it out, puts it back and says to his caddie, if I AM GOING TO LAY UP I'm really going to lay up and he grabs his wedge, hits it beautifully about 45 yards short of the pond, it hits a sprinkler head right in the middle of the fairway---KABOINK--and takes off into the air and travels about 50 more yards in the air right into the pond and there goes the US Amateur by one shot!