硬海绵或硬骨海绵曾作为硬海绵纲（Sclerospongiae，也称硬骨海绵纲）分类在多孔动物门中，最初是由Hartman和Goreau在1970年设立，但之后Vacelet发现在海绵不同的纲里都有硬海绵的存在，表明了硬海绵纲不是具有亲缘关系的一组海绵分类单元。因此在新的分类里，这个纲被解散了。

硬海绵的寿命可达500－1000年。

硬海绵包括Ceratoporella nicholsoni、Stromatospongia vermicola、Hispidopetra miniana、S. norae、Goreauiella auriculatra以及Merlia sp.，是由J. C. Lang等人在1975年详细描述。

Sclerosponges are sponges with a soft body that covers a hard, often massive skeleton made of calcium carbonate, either aragonite or calcite. Because of their long life span (500-1,000 years) it is thought that analysis of the aragonite skeletons of these sponges could extend data regarding ocean temperature, salinity, and other variables farther into the past than has been previously possible. Their dense skeletons are deposited in an organized chronological manner, in concentric layers or bands. The layered skeletons look similar to reef corals. Therefore, sclerosponges are also called coralline sponges.