In molecular nanotechnology, which term is used for possibility of badly or maliciously designed self-assembling structures that could get out of control, and destroy or disassemble all structures they encounter in their blind quest to replicate?

The 'gray goo' scenario describes the hypothetical risk of self-replicating nanobots (molecular assemblers) gone out of control, endlessly consuming all matter while replicating. The term was popularized by Eric Drexler in 'Engines of Creation' (1986). The other colors (blue, green, red goo) are not standard terms in nanotechnology risk discussions.