Callyspongia aculeata

Acclimation: like all invertebrates it is very sensitive to even minor changes in water chemistry; acclimate it slowly, by floating or drip, without rushing. Above all, NEVER take it out of the water, whether at purchase, in transport or during acclimation: even brief contact with air traps bubbles in its pores that block the flow of water, and the colony then starves or decomposes.

Placement: put it in moderate to strong flow that brings food and carries waste away, but never where air bubbles can be forced into the colony (skimmer outlet, agitated surface). For most sponges light matters little; strong light grows algae on the colony, which clogs its pores and stops it feeding.

Difficulty: Meerwasser-Lexikon rates it 'not suitable for aquarium keeping' and, if you try, recommends at least 200 litres. In the wild it lives in rather cool reef water (20 to 24 °C according to Wikipedia): keep that in mind if your tank runs warm.

Signs to watch: a sponge that has been exposed to air often dies slowly, in patches; a colony that loses colour, gets covered in algae or decomposes is starving or smothering. Do not leave it to rot in the tank. Also avoid copper treatments in an invertebrate tank.

Like all sponges it is a filter feeder: it draws water in through its pores and retains phytoplankton, zooplankton and fine particles. It feeds almost constantly and needs supplemental feedings (a fine food for filter-feeding invertebrates) to thrive in a tank.