This research project aims to chart the complex relationship between marine biology and the built environment, beginning with fish and algae. We can trace the history of many urban developments and built landscapes by considering the human activities centred on marine resources. Often considered as separate universes, the sea and the shore live in a continuum characterized by constant social and physical interactions. Take, for example, sardine fishing or the use of sargasso as an agricultural nutrient: each activity provides a livelihood and promotes economic development but also calls for specific architectural devices. Following the sardine or the sargasso leads us to their impact on onshore construction, ranging from the development of large industrial canneries to the shaping of the landscape for agricultural purposes. The trail even allows for links to be drawn between the two activities, as often the same people work in the fisheries in the summer and the fields in the winter. Hence, it is possible to think of architectural history through a biological lens and to connect the complex ecology of the sea with the no less complex transformation of the built environment on land.