This felt like the most obvious explanation to me as well. Maybe the artist's vision for it was a solid cube of cash, but it ended up needing a structure inside to support the thing.

So many reasons this might be exactly $1,000,000 but not sum up on the outside.

That said, this is also something I would have spent way too much time overthinking, so I thoroughly enjoyed reading the blog post.

Not until Nicolas Cage gets involved.

there's only one way to find out

Did you read the article?

> What if it’s hollow? You can only see the outer stacks. For all we know, the middle is just air and crumpled-up old newspaper. A money shell. A decorative cube. A fiscal illusion. The world’s most expensive piñata (but don’t hit it, security is watching).