  Recently a class of molecular graphs, called altans, became a focus of
attention of several theoretical chemists and mathematicians. In this paper we
study primary iterated altans and show, among other things, their connections
with nanotubes and nanocaps. The question of classification of bipartite altans
is also addressed. Using the results of Gutman we are able to enumerate
Kekul\'e structures of several nanocaps of arbitrary length.
