You can curse crates and the likes. They also give back mana if you hit them with the Mage’s Mana Strike. Not sure if it is intentional.
They also produce Putrid Wraiths with Lich’s Wraith Bringer passive. I call it “Wraith in a box”.
Thanks for the report, we’re taking a look at our breakables to ensure we do not continue to smite them with great vengeance.