I've been living with this one awhile so as to enjoy it--and puzzle over it!-- before parting with it. Is it in fact two interlocked pieces, fit so tightly there is no give whatsoever between them? My guess is no, that it is one piece of wood, incised to appear that way--or perhaps a puzzle whimsy etched out but never actually carved. Still, it appears like two different pieces, with the grain of the wood, to my eye at least, not seeming quite to match. I love it as a very satisfying physical object, and as a mystery, feeling a bit like a mobius strip.
3 3/4" t x 1 5/16" x 1 5/16" and in beautiful condition, with nice age and patina.