Things becomes less clear when you take supersampling into account. Samples may be taken in a quincunx pattern for instance. But these samples are usually call

Things becomes less clear when you take supersampling into account. Samples may be taken in a quincunx pattern for instance. But these samples are usually called fragments, not pixels. They turn into little square pixels later in the pipeline, so yeah, I guess that pixels really are little squares, or maybe little rectangles.