They were pretty gentle with it Mike, but it was in surprisingly solid condition and could be slung onto the truck (the truck belongs to NZs oldest boat moving company so they know what they're doing). Also, they were having to work quickly in between tides. Being that it was completely buried in sand for most of its life, the lack of oxygen and damage from the elements probably helped to preserve it. Also it would not have moved at all since it was buried (which happens quite quickly to objects on Muriwai beach, (being on the often wild West coast) which extends for around 60km and the sand is a black iron-sand.
Once removed a fuel tank from a VW beetle there in the late 70s, which was buried up to the windows and just a shell, after being rolled around in the surf for a few days and shedding all its' bits. Fitted the tank in my modified Ford popular.