I think the more specific term you're looking for is "pareidolia", which can be defined as seeing images in places where they are not supposed to be (like a devil's face in a cloud of smoke, for example).
Pareidolia is a "coincidence" of sorts, whereby random chance, the workings of physics or photographic anomalies appear to produce patterns that approximate some other, recognized form. But more than mere coincidence is required to explain or describe the second part of the pareidolia equation, which is a purely mental and/or visual phenomenon.
Even having studied Michelangelo's work since childhood, I cannot declare with authority or confidence whether we are seeing pareidolia/coincidence at work in these organ-like shapes in the Sistine Chapel frescoes, or whether, as some claim, the artist painted them in of his own initiative and volition.
But I will repeat that I find it extremely unlikely that an expert anatomist such as Michelangelo, who is known and documented to have dissected and examined human cadavers throughout his lifetime, would have "accidentally" or "coincidentally" painted human organs into figurative shapes where those organs did not belong.
As I stated upthread, Michelangelo was a meticulous planner, who sketched in excruciating detail the figures and forms which he then transferred onto the surfaces of his paintings. I find it highly unlikely that a brain stem, for example, would have "accidentally" appeared in a certain painting of his of a neck, especially when all other necks he painted did not show those same, brain-stem-like forms.
In closing, we don't see "helicopters and spaceships" in his work primarily because Michelangelo painted the rounded, organic forms of the human figure almost exclusively, barring only fabrics draped over such figures, masonry and architectural elements which have the verisimilitudinous look of imperfect handicraft, and incidental props such as martyrs' relics. He did not typically paint vehicles, vessels or other such objects which would lend credence to the identification of modern, hard-lined, post-industrial technologies in his work.