What is this thing, and can I get a replacement?

It broke when I tipped over on my bike.   I didn't even know that it had broken until it clunked down and was interfering with the pedaling action.  It must have a name but I can't find one online to order.   Seems like not such a big deal, but it did prevent my leg from getting greasy when I ride, plus it seemed a bit of a protection from those pokey bits on the gear. 

Tipping over was just a dumb thing I did.  I don't even know what I was doing, I think I was trying to reach down and check my tire pressure on the front tire - while slowly riding on my driveway...or maybe I was feeling the front brake pad.  I don't know why I didn't stop and do whatever it was I was trying to do, silly.  And before I knew it I was falling, unable to stop it.  I was okay.  The bike thingy broke.

I'd like to replace it.