  According to microscopic calculations with antisymmetrized molecular
dynamics, we studied cluster features in stable and unstable nuclei. A variety
of structure was found in stable and unstable nuclei in the $p$-shell and
$sd$-shell regions. The structure of excited states of $^{12}$Be was
investigated, while in $sd$-shell nuclei we focused on molecular states and
deformed states. The deformed states in $^{28}$Si and $^{40}$Ca were discussed
in connection with the high-lying molecular states. Appealing molecular states
in $^{36}$Ar and $^{24}$Mg were suggested. The results signified that both
clustering of nucleons and mean-field formation are essential features in
$sd$-shell nuclei as well as $p$-shell nuclei.
