Tectitethya crypta

Tectitethya crypta (formerly known as Cryptotethya crypta and Tethya crypta) is a species of demosponge belonging to the family Tethyidae. It is a massive, shallow-water sponge found in the Caribbean Sea. Oftentimes, it is covered in sand and algae.

The nucleosides spongothymidine and spongouridine were isolated from this sponge, providing the basis for anti-viral drugs and anti-cancer drugs. Vidarabine, an antiviral drug, was derived from these compounds. The discovery of these nucleosides also led to the development of cytarabine for clinical use in the treatment of leukemia and lymphoma. Gemcitabine, a fluorinated derivative of cytarabine, is used to treat pancreatic, breast, bladder, and non-small-cell lung cancer.