WHAT is on my feet?

This little girl has been barefoot for most of her life.  We've put shoes on her a couple of times recently, and they are such a strange concept to her.  The Robeez seem to be a good start .  At first I put shoes on her with thick soles, she wouldn't stand and just went weak at the knees.  I figure we better start getting her used to shoes since it may start cooling off, and she is getting closer to walking.

Where'd my foot go?

What is this thing?