A capsule comprising: a capsule body having a bottom , a side wall , an end opposite of the bottom and a flange extending outwardly from the side wall and around the open end ; and a cover attached to the outwardly extending flange , the cover closing off the end of the capsule body opposite of the bottom ; the capsule body and the cover bounding a capsule chamber , the capsule chamber containing: a substance constituted by a mass of loose, solid particles, for the preparation of a potable beverage by extracting and/or dissolving the substance by means of supplying a fluid under pressure into the capsule , and a screen , permeable to water and impermeable to a predominant portion of said particles, said screen being positioned between said substance and said bottom , said screen having a centre; characterized in that the screen is arranged to move away from the centre area of the bottom under influence of piercing elements by means of which, in use, openings are pierced in the bottom of the capsule for injecting fluid into the capsule and/or under influence of fluid injected via openings in the bottom which openings are created by means of a coffee machine wherein the capsule is positioned for brewing coffee, and in that said screen is attached to said capsule body along attachment zones spaced from the centre and circumferentially spaced from each other. a capsule body having a bottom , a side wall , an end opposite of the bottom and a flange extending outwardly from the side wall and around the open end ; and a cover attached to the outwardly extending flange , the cover closing off the end of the capsule body opposite of the bottom ; the capsule body and the cover bounding a capsule chamber , the capsule chamber containing: a substance constituted by a mass of loose, solid particles, for the preparation of a potable beverage by extracting and/or dissolving the substance by means of supplying a fluid under pressure into the capsule , and a screen , permeable to water and impermeable to a predominant portion of said particles, said screen being positioned between said substance and said bottom , said screen having a centre; characterized in that the screen is arranged to move away from the centre area of the bottom under influence of piercing elements by means of which, in use, openings are pierced in the bottom of the capsule for injecting fluid into the capsule and/or under influence of fluid injected via openings in the bottom which openings are created by means of a coffee machine wherein the capsule is positioned for brewing coffee, and in that said screen is attached to said capsule body along attachment zones spaced from the centre and circumferentially spaced from each other. a substance constituted by a mass of loose, solid particles, for the preparation of a potable beverage by extracting and/or dissolving the substance by means of supplying a fluid under pressure into the capsule , and a screen , permeable to water and impermeable to a predominant portion of said particles, said screen being positioned between said substance and said bottom , said screen having a centre; characterized in that the screen is arranged to move away from the centre area of the bottom under influence of piercing elements by means of which, in use, openings are pierced in the bottom of the capsule for injecting fluid into the capsule and/or under influence of fluid injected via openings in the bottom which openings are created by means of a coffee machine wherein the capsule is positioned for brewing coffee, and in that said screen is attached to said capsule body along attachment zones spaced from the centre and circumferentially spaced from each other. <EOS>