Explants of the tropical sponge Pseudosuberites andrewsi were fed with the marine diatom Phaeodactylum tricornotum. The food was supplied either as intact algae or as a filtered crude extract. Growth (measured as an increase in underwater weight) was found in both experiments. The explants fed with intact algae increased to an average underwater weight of 255% of the initial weight in 45-60 days. The explants fed with crude extract increased to an average of 200% of the initial weight in 30 days. These results show that it is possible to grow a sponge using a single microorganism species as a food source. In addition, it was demonstrated that sponges are also capable of growing on non-particulate food. Therefore, this study is an important step forward towards the development of controlled, in vivo sponge cultures.