The glossy slab had arisen from the waters of the murky lake high in the mountains above the city. The base was obscured by a faintly pulsating glow deep in the sanguine water. Tiny excited ripples, as those of music in an adjacent room, danced where the sides met the surface. An overbearing bass hum reverberated through the water into every bay and reed-bed, causing distress amongst the fish and arthropods inhabiting the normally-silent ecosystem. On land it would only be perceptible as an anxious feeling of foreboding.
It was three days before anyone noticed.