Burr puzzle - Wikipedia

File:Six-Piece Burr - Burr 305.svg - Wikipedia

Interlocking Burr Puzzles

List of unsolved problems in mathematics - Wikipedia

Jigsaw puzzle - Wikipedia

Burr puzzle - Wikipedia

LEGO MOC LEGO 3-Piece Burr Puzzle by weixinf

A simple 'Burr' puzzle.

Jigsaw puzzle - Wikipedia

Burr puzzle - Wikipedia