What is hidden in 3D image?

The Ultimate Computer stood at the end of the Ultimate Computer Company's production line. At which point the guided tour eventually arrived.
The salesman stepped forward to give his prepared demo. 'This,' he said, 'is the Ultimate Computer. It will give an intelligent answer to any question you may care to ask it.'
A smart-aleck who ran a humor mailing list stepped forward and asked, 'Where is my father?'
There was the soft hum of powerful electronic gear going to the task. Panel lights lit and blinked, and within a couple of seconds the laser printer printed out a piece of paper: 'Fishing off Florida.'
The smart-aleck laughed, 'Actually, my father is dead! It was a trick question.'
The salesman, quickly thinking on his feet, replied that he was sorry the answer was unsatisfactory, but as the Ultimate Computer was precise, perhaps a rewording of the question might work better.
The smart-aleck said to the Ultimate Computer, 'Where is my mother's husband?' Again, the hum of the powerful electronic brain filled the room.
After a moment, the laser printer whirred to life. The paper said, 'Dead. But your father is still fishing off Florida.'