Sponges are ecologically and commercially important organisms whose simply organized cellular structure makes them especially amenable to cell culture. Cells cultured in vitro can increase our understanding of sponge cell growth and metabolism, and may reduce the need for wild sponge harvest for biomedical research, pharmaceuticals, and aquaculture. Recent studies have proven the ability to culture marine sponge cells in two-dimensions using an optimized nutrient medium. Here we demonstrate the successful implementation of multiple three-dimensional cell culture methods to culture cells from the marine sponge Geodia neptuni using the same optimized nutrient medium. The results of this research will advance current sponge cell culture methods, and further optimization of these techniques may lead to the in vitro production of marine natural products to meet biomedical demands and the culture of important marine sponge species for habitat restoration.