Architects have used a biological vocabulary for decades, especially when describing the city. Often this vocabulary has drawn from certain cellular processes and body functions. Drawing parallels between a city’s flow and biofluid dynamics, Architects turned to the circulatory system for lexical inspiration. For example, the word “veins” has been used for over a century to describe a city’s streets, boulevards, and avenues–with its main thoroughfares and highways referred to as “arteries.” With increasing awareness of the efficiency and intelligence of biological processes, there is a growing movement to adopt more of these processes into architecture. Building upon these trends, this paper will show how coral reefs are an effective source of solutions for architecture, urban planning, and design. This paper will compare two complex ecosystems—one urban and one marine–to highlight the connection between reefs and cities. A reef is an efficient and fertile agglomeration of biological structures; the complexity of a coral reef allows for the production, consumption, and reproduction of millions of organisms. Compared to traditional city construction, where design caters to only one species, could coral reefs suggest different design mechanisms to increase a city’s biodiversity thus enhancing sustainability?