Wooden Puzzle

Found in a charity shop, about the size of a Rubik's cube....carefully transported it home, afraid if it came apart I'd not get it together again...

Then I found the problem is actually to get it APART to start with...!

Normally I'm okay at dismantling...(okay, breaking...) things but this one's got me beat...gentle force and encouragement might work, but can't believe that's the solution...

Never mind, the shape intrigued me as being something like one of those Escher type impossible 3D drawings, with staircases etc. going in all directions...