  Context: Except for the Ca II resonance lines, fibrils are ubiquitously
present in most high-resolution observations of chromospheric lines. Aims: We
show that fibrils are also a prevailing feature in Ca II K, provided the
spatial-resolution is sufficiently high. Methods: We present high spatial
resolution observations of an active region in the Ca I} K line from the
Swedish Solar Telescope. Through a comparison between photospheric intensity
and magnetic field data, we study the connection between bright chromospheric
fibrils and photospheric structures. Additionally, using Fourier analysis we
study how the fibrils are linked to the observed dynamics. Results: We find
that very narrow, bright fibrils are a prevailing feature over large portions
of the observed field. We also find a clear connection between the fibril
footpoints and photospheric magnetic features. We show that the fibrils play
two distinct roles in the observed dynamics: depending on their location they
can act as a canopy suppressing oscillations or they can channel low-frequency
oscillations into the chromosphere. Conclusions: The Ca II K fibrils share many
characteristics with fibrils observed in other chromospheric lines, but some
features, such as the very small widths, are unique to these observations.
