This visualization displays the adjacency matrix of a dolphin social network, showing connections between individual dolphins as blue cells against a white background. It loads real network data from a GitHub Gist using `d3.text`, parses the edge list, and builds a symmetric matrix to reflect the undirected graph. The code uses core D3.js v7 methods like `d3.select`, `selectAll`, and `data().enter().append()` to render the SVG rectangles, with row groups positioned via `transform` attributes and cell fills determined by binary connection values. Tooltips are included but not bound to mouse events in the provided code.