Homade landscape irrigation?

Specific Inspection Topics Plumbing Inspections
1

Is that what this is? What’s the bulbous thing inline near the bottom of the photo?
And why is it shaped like that? Looks like it used to go around something.

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2

http://www.homedepot.com/p/Mueller-Global-1-1-2-in-PVC-Check-Valve-101-107HC/100198425