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 and anti-cancer drugs like Aciclovir.