A two piece burr? Who ever heard of such a thing?
Ah, Frank Potts did.
This is a 2 piece puzzle that is one of the most minimal fully interlocking puzzles out there. Two pieces come together and, after a brief dance, form a cross. An interesting outlier, a mathematical curiosity, or just a cool puzzle - no matter how you see it, it's pretty neat.
Previously available as an IPP Exchange puzzle; reproduced with express permission from the designer.