  The current standard model of cosmology, $\Lambda$CDM, requires dark matter
to make up around $25\%$ of the total energy budget of the Universe. Yet, quite
puzzlingly, there appears to be no candidate particle in the current Standard
Model of particle physics. Assuming the validity of the cold dark matter (CDM)
paradigm, dark matter has evaded detection thus far either because it is
intrinsically a weakly interacting substance or because its interactions are
suppressed by its high constituent mass and low number density. Most approaches
to explain dark matter to date assume the former and therefore require
beyond-the-Standard-Model particles that have yet to be observed directly or
indirectly. Given the dearth of evidence for this class of candidates it is
timely to consider the latter possibility, which allows for candidates that may
or may not arise from the Standard Model. In this work we extend a recent study
of this general class of so-called macro dark matter--candidates with
characteristic masses of grams and geometric cross sections of cm$^2$. We
consider new bounds that can be set using existing data from the resonant bar
gravitational wave detectors NAUTILUS and EXPLORER.
