  Observations of magnetism in very low mass stars recently made important
progress, revealing characteristics that are now to be understood in the
framework of dynamo theory. In parallel, there is growing evidence that dynamo
processes in these stars share many similarities with planetary dynamos. We
investigate the extent to which the weak \emph{vs} strong field bistability
predicted for the geodynamo can apply to recent observations of two groups of
very low mass fully-convective stars sharing similar stellar parameters but
generating radically different types of magnetic fields. Our analysis is based
on previously published spectropolarimetric and spectroscopic data. We argue
that these can be interpreted in the framework of weak and strong field
dynamos.
