noun

a long, narrow opening or line of breakage made by cracking or splitting, especially in rock or earth.

the bacteria survive around vents or fissures in the deep ocean floor

opening,crevice,crack,cleft,cranny,chink,slit,groove,gap,hole,breach,aperture,vent,interstice,crevasse,chasm,ravine,crater,break,fracture,fault,rift,rupture,split,rent,gash,scission,grike

verb

split or crack (something) to form a long, narrow opening.

the dry years had cracked and fissured the cliffs