A gas distribution plate for fluidized-bed, olefin polymerization reactors is provided. In addition to holes for distributing a fluidizing gas, the plate comprises a plurality of hollow projections for introducing a fluid into the fluidized-bed reactor. The hollow projections, which can be tubes or pipes, extend above the plate towards the fluidized bed and serve a number of purposes. The projections can break apart or penetrate fallen polymer agglomerates or sheets. They can be equipped with flow or pressure sensors to detect a decrease in flow rate or an increase in pressure drop across the projections, which is an indicator of the presence and/or size of fallen polymer agglomerates or sheets. The projections can also break apart the agglomerates or sheets into smaller pieces by delivering blasts of fluid directly into the agglomerates or sheets. The projections can also be used to inject a kill agent into the fallen agglomerates or sheets, or collapsed portions of the bed, to speed up penetration of the kill agent into the agglomerates, sheets, or collapsed portions.