Recent studies suggested that a small sub-population of embryonic stem (ES) cells exhibit 2-cell stage embryo-like (2-cell-like) features, including the reactivation of murine endogenous retrovirus with leucin transfer RNA primer, high histone mobility, and dispersed chromocenters. Furuta et al. investigated the organelle morphology of 2-cell-like cells using electron microscopy (Furuta et al. Lipid droplets are formed in 2-cell-like cells. pp. 79–81). They demonstrated the formation of a lipid droplet during the transition from ES cells to 2-cell-like cells, and proposed that these cells utilize a unique energy storage and production pathway.