Endemic Interstices targets the production of proto-architectural entities as a bottom up system with the capacity to self structure, adapt and co-evolve within the environment considering natural resources as part of a tectonic system.The project aims to create synthetic ecologies by harvesting the physics of natural processes not only as a design generator but also as a tool for fabricating complex formations by computation of matter. More specifically the main driver of our thesis is a nonlinear fabrication technique that utilises cracks in clay soil as a formwork for casting intricate structures. By programming the material behaviour and exposing it to certain environmental condition we are able to control the emergence of a wide range of crack patterns which are responsible for different performative qualities such as structural stability, solar shading and airflow modulation consequent to their morphological features of different size, density and porosity. The deployment of the system on site employes earth works protocols and Top Down construction techniques in order to achieve a temporary scaffold. These features and qualities are explored through physical experiments and digital simulations at various scales. As a result, different crack morphologies are articulated together into a new tectonic language.