Significance for people
In some Asian cultures, like Japan these sponges are given as good luck charms, like horseshoes, to couples getting married as they often have two tiny shrimps living in symbiosis inside the sponge’s body cavity, always a male and a female. They swim in as larvae and then get trapped inside the sponge’s mesh-like tissues as they grow to adults. They are perfectly happy though as they feed off the filtered food debris left by the sponge! Any young can escape from the sponge as they are small enough to swim through the mesh of the sponge’s tissue and can move to find their own sponge as a home.
Many people may well have encountered these cleaned and dried “skeletons” of these sponges in an art class or seen them in a Victorian glass dome display as they have always been popular for their delicate beauty. Occasionally it is used in marine aquaria.