A collection of compressible particles. The compressible particles are intended to be used for attenuating pressure build-up within a confined volume such as a trapped annulus in a wellbore. Each of the compressible particles is fabricated to collapse in response to fluid pressure within the confined volume, and comprises carbon. Particularly, each of the particles comprises a plurality of peripheral openings, permitting an ingress of wellbore fluids in response to an increase in pressure within a trapped annulus. The collection of compressible particles together has a reversible volumetric expansion/contraction of ≥10% and up to 25% at pressures up to 10,000 psi. A method of attenuating annular pressure buildup within a wellbore using the collection of compressible particles is also provided.