Real headscratcher...Steam heat part?

[Diggit]

Found this about 10" down with a White's MXT in relic mode, using a 10x12" SEF coil. It was on the edge of a non used baseball field, the area used to contain homes from the early 1800s, they were torn down in the 80s.

 

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[taz42o]

Blow though it, does it whistle? Does air only go through in one direction?

 

[Diggit]

Blow though it, does it whistle? Does air only go through in one direction?

Neither. It is so corroded that no matter of soaking or forcing objects or water through it can make a clear opening.

It's frigging frustrating. I THINK it may be a "release valve" for a steam register, but I can't find one that looks like it.

 

[roscoerossie]

It looks like a fountain pen cap

 

[digging wv]

too big for a fountain pen