Spongeguide.org
Sponges are one of the more beneficial invertebrates for reef aquariums due to their great ability to filter DOM and bacteria out of the water. Plus they are colorful, have interesting shapes and many have modest husbandry requirements if properly fed.
A new guide for Caribbean sponges is available at spongeguide.org. They have more than 170 sponge species in their database.
“Your photographic guide to over 170 species of sponges found on Caribbean coral reefs and associated rocky and lagoon environments.”