Modularity refers to a pattern of connectivity in which elements are grouped into highly connected subsets, modules or building blocks. It is an important property in biology, as it helps a system to "save its current state" while allowing further evolution. Developmental modules are often represented by their physical location and spatial extent in the organism, and they contain informations about the genetic specification of modules. Thus, the properties attributed to modules are: autonomy, discrete organization defined by the expression of specific genes, and occupation of specific physical territories. In vertebrates, the functional and architectural organization of the olfactory system is conserved throughout evolution. The olfactory organ is composed of different types of olfactory sensory neurons, the OSNs, each capable of detecting specific odorant molecules, organized with a specific shape and position, and each expressing a specific set of genes. The hypothesis of the ZOORRO project is that each type of OSNs could be defined by specific modules at key stages of the embryonic development of the olfactory organ. This project aims at breaking down the formation of the olfactory sensory organ into modules: a genetic module and a morphometric-behavioral module. A multidisciplinary consortium of three teams will use a combination of qualitative and quantitative imaging on the zebrafish embryo (Julie Batut, CBI-MCD Toulouse), data science, machine learning and image analysis (Christian Rouvière, CBI Toulouse) together with mathematical models (David Sanchez, INSA Toulouse) to identify the two modules and assemble them to generate a single-cell transcriptomic atlas dynamically linked to cellular behavior and capable of predicting the architecture of a complex biological system: herein, the olfactory sensory organ.