Help identifying this component {Diode}?

[OffGrid-on-Rocker]

This is from an Electric Fence Controller from I think 1970's.{Bull dozer brand} .
I do not see any markings.
Thanks

 

[Minder]

Looks like a spark gap, either for over voltage or for initiating the firing point?
M.

 

[OffGrid-on-Rocker]

thanks

 

[duke37]

What is the supply voltage. The rust would indicate that it might have been used outside and be battery driven, then the input voltages would be low.

It should be possible to sketch out the schematic with such a simple circuit.

 

[OffGrid-on-Rocker]

The supply voltage is 120 volts ac. I understand most of the circuit{I am just a beginner} . I understand the timer circuit how it charges the capacitors and discharges through the SCR. but not sure what the spark gap does. The MOV is completely destroyed.