Sponge id

[reefer295]

Can anyone help me ID these sponges? There are three of them next to each other and they seem to only be growing in the shade. My tank is about 3 years old and I noticed the sponges a few weeks after I bought a black sun coral. Does anyone know how fast they will grow, and if it will expand into lit areas of the tank?

 

[lil sumpin]

I got several of these on my rock. There’s some that’s also grown on the stalk of my torch. Hasn’t harmed the coral though, I think they’re harmless @ISpeakForTheSeas

 

[ISpeakForTheSeas]

Sponge ID can be very tricky, particularly if the sponge doesn't have any easily recognizable characteristics (like the pineapple-esque shape of pineapple sponges) - microscope pics of the spongin and spicules is recommended for ID purposes.

Based on how tightly the sponge is hugging the shadows in the pics, I would guess it's a relatively cryptic species - it may expand into the light at some point, but I wouldn't expect it to be invasive personally.

here’s a good Sponge ID resource for anyone who’s interested- as mentioned, though, sometimes DNA is the best indicator for telling sponges apart:
https://www.fao.org/3/i7773e/i7773e.pdf And, here’s a decent example of why sponge ID by non-microscopic sight is not always reliable:
https://www.researchgate.net/figure...rating-variations-in-shape-and_fig6_248716402

Yeah, that's definitely a sponge. Most sponges are completely harmless/beneficial, but some can be invasive and/or harmful to corals (thankfully, these are rare).

To tell if a sponge is chemically harmful: if a healthy, established coral starts closing up or looking to be in bad shape on the side closest to the sponge as the sponge grows closer to it, and nothing else has happened (lighting changes, parameter swings, pests, etc.) that could explain it, then the sponge is probably chemically harmful.

Chemically harmful sponges are very rare.

For invasive sponges: unless it shows signs of being chemically harmful or starts actively growing over and smothering a coral's flesh/polyps, it's harmless. These can grow over the skeletons of corals, around the base/stalks of corals, even up into the water column above corals (where they're over the coral but not growing on the flesh or polyps themselves), etc. without harming the coral at all - as long as the coral flesh and polyps can get food, light, and flow, the sponge is harmless.

Invasive sponges are moderately rare.

Invasive and chemically harmful sponges are incredibly rare.

 

[reefer295]

Thank you

 

[reefer295]

Do you think it came on the black sun coral? They both like the shade.

 

[ISpeakForTheSeas]

Do you think it came on the black sun coral? They both like the shade.

It's definitely possible- some sponges can grow from single cells, so it's entirely possible it may not have been visible without a microscope when it entered your tank.