Clustering in nuclei can be viewed as the emergence of molecular-like substructures within the nuclear many-body system. In such cases, the complex dynamics of nucleons may be effectively described in terms of a few interacting clusters, providing a simplified and intuitive picture of atomic nucleus. In this talk, I will try to address two questions: how do these molecular-like substructures emerge from the underlying inter-nucleonic interactions, and what are the experimental signatures that may help us  identifying them ?
I will first discuss clustering in light nuclei, with the emblematic example of ^{12}C and its Hoyle state, from an ab initio perspective. I will present preliminary results and highlight how symmetry breaking and restoration techniques allows to efficiently capture collective behaviour, which are typical of clustered states. I will also briefly outline an ongoing collaboration with experimentalists at LPC aimed at constraining the Hoyle state’s matter radius. In the second part of the talk, I will turn to an exotic cluster decay modes : the  double-alpha decay. In 2021, this decay channel was theoretically predicted to be within experimental reach. Out of the several experimental campaigns aiming to probe double alpha decay, I will focus on the one that took place at Isolde in 2023. The results for this search will be presented.