Agaroid structures in the form of an agaroid matrix, a sintered agaroid, or an agaroid mat are disclosed which may, in some embodiments, include a chemically crosslinked agaroid, a derivatized agaroid, and/or an agaroid coupled with one or more ligands. The agaroid structures may be formed by precipitation from a glycol solution, in some cases, and may be converted to be insoluble in water below 40C. In another aspect, methods of treating a condition of a mammal are disclosed, which include contacting an area of a mammalian body with a composition having an agaroid structure with or without one or more beneficial agents. In yet another aspect, the present disclosure provides methods of filling or bulking tissue in a mammalian body by implanting a converted agaroid composition into the mammalian body, which may include converted agaroid microbeads and/or converted agaroid particles.
