Spongolite from the State of Mato Grosso do Sul, Brazil, contains the remains of fossil sponges and hollow needles or microcapillaries with uniform surfaces. The central tunnels are ~1/10 to 1/2 of the cylinder’s diameter. The material is essentially X-ray amorphous though it contains small amounts of orthosilicic acids. The other main elements were Ti and Fe. Spongolite may have uses as a sorbent, as a bioavailable silicon source or, after blending with glass waste, it can be used in the fabrication of lightweight products having a closed-cell structure, potentially useful as an industrial insulator.