Gross looking stuff on my sea lettuce. ID please?

[SeViN]

So today as I was looking at my sea lettuce, I saw white stuff on my sea lettuce. I looked closer and the white fungal looking stuff wasn’t the only thing on it. There were wart looking things on them as well. Any ideas on what these are? Friends or foes?

Also the last pics, I saw this little guy that looks like a star fish. Asterina? Should I take it out?

 

[ISpeakForTheSeas]

Sponges (harmless), pineapple sponges (harmless), and “Asterina” starfish (technically Aquilonastra, but known in the hobby as Asterina).

 

[SeViN]

Sponges (harmless), pineapple sponges (harmless), and “Asterina” starfish (technically Aquilonastra, but known in the hobby as Asterina).

Oh wow, they're so alien looking lol. Will they hurt the sea lettuce? And I read the starfish could start eating corals as well?

 

[ISpeakForTheSeas]

Oh wow, they're so alien looking lol. Will they hurt the sea lettuce? And I read the starfish could start eating corals as well?

Unless the non-pineapple sponges grow over it enough to keep it from getting light, no - the sea lettuce will be fine. (Pineapple sponges are totally harmless; most other sponges are harmless too, but a few can be problematic.) Info dump for the starfish:

Personally, I like them, but they do tend to reproduce very quickly.

I've heard some species eat corals and others don't - I've seen convincing evidence for one species (a very darkly colored one), and one piece of somewhat convincing evidence for one different species, but the vast majority of these guys seem to be at least mostly safe.

With regards to whether or not the average "Asterina" (technically Aquilonastra - Asterina is a separate genus within the Asterinidae family) eat corals, it might be a species specific thing, it might be a you have way too many starfish so they're out of other food options thing, it might be they're eating the slime coat/mucus on the coral rather than the coral itself (see below), or they might just opportunistically eat unhealthy corals. Based on how starfish eat, it seems plausible to me that it may also be coincidental (i.e. the star goes to eat something off the coral and the coral just happens to be one that is able to be negatively effected by the star's everted stomach). Regardless, Zoas are just about the only coral I've heard about regular "Asterina" stars potentially going after with any sort of frequency.

A quote I like to refer to for this:

It's an Aquilonastra spp. starfish and is a great scavenger. I see them with anywhere from 4 to 12 legs. The whole discusion around them seems to me excellent examples of misidentification, mistaken behaviour and assumed causality based just on heresay without looking at the research. Asterina spp starfish are preditary but only reproduce sexually and are shortlived so while it's possible some might get into a tank even if it did happen it's not going to be around long. Aquilonastra are one of the uncommon species that reproduce fissiparous or by splitting so are easy to identify by the different sized legs regrown after splitting. They perform an important function not only feeding off algae films but also feeding off microbial films including those on corals (at least ones that don't sting). FYI the mucus coating on corals ages and corals have to periodicely shed it to renew it and maintian healthy microbial processes (Ref 1, Ref 2). If Aquilonastra are feeding on zoas or softies I'll argue they are either benign or even beneficial as they may be reducing the unhealthy older mucus which can be full of unhealthy microbes which the animal is trying to get rid of and are far more likely to be the actual problem.

Here's an example, this Toadstool is doing one of it's periodic sheddings. The Aquilonastra have been in this system for years but only climb onto the Toadstool when it's shedding. In the first picture you can see the old mucus film, Aquilonastra starfish and areas they have cleaned off. The second picture shows the Toadstool a week later.

 

[SeViN]

Unless the non-pineapple sponges grow over it enough to keep it from getting light, no - the sea lettuce will be fine. (Pineapple sponges are totally harmless; most other sponges are harmless too, but a few can be problematic.) Info dump for the starfish:

Ah thank you so much for the info! Glad I dont have too much to worry about XD