REMOVING floor-to-ceiling walls at the top of a stairway can turn an upstairs hallway or room into a light and airy landing and also bring increased light and openness to the stairwell. For safety, the floor surrounding the stairway must be partly enclosed. One solution is to install a railing around the opening.
A sponge is a member of the phylum Porifera. It is a simple animal with many cells, but no mouth, muscles, heart or brain. It is sessile: it cannot move from place to place the way most other animals can. A sponge is an animal that grows in one spot like most plants do.Nevertheless, sponges are quite successful. sponge is a member of the phylum Porifera. It is a simple animal with many cells, but no mouth, muscles, heart or brain. It is sessile: it cannot move from place to place the way most other animals can. A sponge is an animal that grows in one spot like most plants do. Nevertheless, sponges are quite successful.
Many sponges have internal skeletons of spongin and/or spicules of calcium carbonate or silicon dioxide. All sponges are sessile aquatic animals. Although there are freshwater species, the great majority are marine (salt water) species, ranging from tidal zones to depths exceeding 8,800 m (5.5 mi).