  Being able to measure time, whether directly or indirectly, is a significant
advantage for an organism. It permits it to predict regular events, and prepare
for them on time. Thus, clocks are ubiquitous in biology. In the present paper,
we consider the most minimal abstract pure clocks and investigate their
characteristics with respect to their ability to measure time. Amongst other,
we find fundamentally diametral clock characteristics, such as oscillatory
behaviour for local time measurement or decay-based clocks measuring time
periods in scales global to the problem. We include also cascades of
independent clocks ("clock bags") and composite clocks with controlled
dependency; the latter show various regimes of markedly different dynamics.
