An abandoned shoe!

Saw this shoe lying abandoned in the play area of the Garden:

A close up view of this abandoned shoe:

Shoe travels in pairs. Where is its better half?
Why would someone abandon one shoe while walking around in one shoe?

Did someone brought this shoe here and dropped it?

What is the story?

And thus mind created a problem out of facts which were none of its business. 
As regards the above questions, I have no clue about the answers.