  Networks of biofilaments are essential for the formation of cellular
structures that support various biological functions. For the most part,
previous studies have investigated the collective dynamics of rod-like
biofilaments; however, the shapes of the actual subcellular components are
often more elaborate. In this study, we considered an active object composed of
two active filaments, which represents the progression from rod-like
biofilaments to complex-shaped biofilaments. Specifically, we numerically
assessed the collective behaviors of these active objects in two dimensions and
observed several types of dynamics depending on the density and the angle of
the two filaments as shape parameters of the object. Among the observed
collective dynamics, a moving density band that we named a `moving smectic' is
introduced here for the first time. By analyzing the trajectories of individual
objects and the interactions among them, this study demonstrated how
interactions among active biofilaments with complex shapes could produce
collective dynamics in a non-trivial manner.
