I’m continuously fascinated by all of the different things that live in our oceans. Sponges are the simplest of the multicellular organisms and also among the oldest, with a fossil record extending back to the last part of the Precambrian period, about 550 million years ago. When I go snorkeling at the fossil reef at Key Biscayne (my local reef) I see all types of sponges; bright red fire sponge, large brown barrel sponges, delicate blue encrusting sponges, etc. They inhabit turtle grass beds and coral reefs alike. Sponges filter the water while providing food and shelter for a myriad of creatures.

Blue Layer Cake Sponge – Collospongia

Sponge close up

For the past few years I have been growing Collospongia, commonly known within the hobby as layercake or blue photo sponge; it has bright blue coloration and grows very similar to Montipora capricornis, in thin spiraling plates. When kept on its own rock it has a stronger tendency to create layers instead of encrusting like other sponges. It is prized for its brilliant blue/violet coloration. Most reefers that see my colony in person mistake it for an sps coral upon first viewing because of its unusual growth pattern.

Side view of the layered growth pattern

This sponge thrives in moderately strong light and high flow. It will create layers much better in an area with good flow, whereas in low flow it will have a tendency to grow more flat and encrusting. This sponge is different from most other sponges in that you can expose it to air for short periods of time without damage. Some people complain about this sponge growing too fast or being invasive, but it is so popular with other aquarists, getting rid of excess growth shouldn’t be a problem. I have nearly killed it with too high alkalinity in the past, but sponges have amazing regeneration capabilities and my colony grew back. If like me, you seek out the unusual, this sponge will definitely be rewarding to grow in your own reef.

Violet Colony of Collospongia that is starting to plate more as it grows larger.