Sponges do not move around much; they are considered to be sessile or fixed in one place. However, research has shown that some sponges can move slowly by shifting their cells in a coordinated fashion. They can reshape themselves to crawl along the seafloor or other surface. They extend parts of their bodies and contract others to achieve locomotion. However, if you attempt to watch a sponge moving, you will likely be disappointed. At best, they move tiny distances, like a couple of millimeters per day. Juvenile sponges are much more mobile. A sponge larva is a little ball of cells with hair-like extensions (cilia or flagella) that allow it to paddle around for a few days until it finds a place to settle down. Once settled, its cells transform to be more appropriate for a sessile organism.