What is this symbol next to (some) T&Co purity marks?

[10rock]

Has anyone else come across this squiggly mark (it looks like a mushroom head on a sphinx to me) on vintage T&Co jewelry?

What does it mean and why do some pieces have it but not others?

Thank you!

 

[glitterata]

It looks like a stud or cuff/collar button. Is it the mark of Krementz? It's similar to Krementz's mark, anyway.