What is this component and what is its use?
As noted in comments, the part shown in the photograph is a spark gap. This page lists several such spark gaps and similar / related parts. 

Below is an inert-gas filled spark gap, closest in functionality to the part in the question, yet safer due to being glass encapsulated:



A more common modern version of this device is offered by Littelfuse and others, and comes in several different packages:



The through-hole versions are available on eBay for around $1 to $2 in single units, if you would like to experiment with one.



Various schematic symbols for spark gaps are documented on WikiMedia:



Of these, symbol #2 is most commonly supported in the schematic software I have used.