Keyhole?

[critter0527]

Found this about 8 inches down at a very active soccer field.

 

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[critter0527]

Pics

 

[BosnMate]

Gotta wonder what it's to

 

[creskol]

size?

 

[critter0527]

I would guess its three to four inches

 

[JOHUNT]

could be a plate cover, like the things on the back of a modern smoke detector

 

[creskol]

I think it is an anchor plate, similar in nature to this one:

 

[BosnMate]

yeah, the nail head fits through the hole and then it hangs on the small part. I have a clock hanging on the wall with exactly the same thing in plastic.

 

[creskol]

I would guess its three to four inches

Is it 3 or four inches? What are the slot measurements? What is it made out of?