How are unnecessary substances removed from unicellular organisms?

In unicellular organisms, as in multicellular organisms, the so-called waste is formed in the process of life, which must be disposed of in order to avoid poisoning and other dangerous consequences of their accumulation. Unnecessary substances are removed from them directly through the shell into the environment according to the principle of lower concentration. But with the liquid, everything is a little more complicated. For this, a special “organ” is used, called the contractile vacuole, which, by contracting, pours the accumulated fluid into the environment.