Is this a sponge?

[scoop]

I've got a few of these growing under the rocks in my tank. You can't really tell from the lousy picture, but it is round and looks soft, but it won't dislodge easily. If not sponge, any ideas what it is? Thanks.

[three90s&125sump]

If it is soft it is prolly a sponge or tunicate.

[Loverotties]

Hard to tell by that pic.

[tdwyatt]

Looks to be a sponge, I cn see several ostra on its surface. Characteristics of sponges include a system of pores and canals (pores are known as ostia), through which they pump water for nutrition and gas exchange as well as waste removal. Water movement is driven by the beating of flagellae located on specialized cells in the ostra and canals called chonocytes (collar cells). Morphologically, sponges display either radial symmetrical or are totally asymmetrical. They are supported by a protein collagen skeleton made stiff (and occasionally painful to human touch) by silicate or calcareous spicules. Skeletal elements, choanocytes, and other cells are imbedded in a gelatinous matrix called mesohyl or mesoglea. Sponges capture food (detritus particles, plankton, bacteria) pelagic on local currents and filter these particulates from the canals driven by choanocytes. Food items are taken into individual cells by phagocytosis, and digestion occurs within individual cells. In closed systems with circumtropical live rock, many of the sponges will be of the silicate-type, reducing and sinking silicates from the water column that would otherwise drive diatom blooms.


Beneficial to your tank.


HTH