Should I be concerned?

[bennett85]

I would like to know if anyone could help me identify what these 2 things are in my saltwater aquarium.
Picture 1 is like an off white with a faint shade of green in it and is roundish and about ¼ inch and has slowly grown over the last 3 weeks.
Picture 2 has 3 like things growing, which are clear and ¼ inch to ½ long and growing slow over the last 2 weeks.
I would like to know if I should take it out or let it grow and see what it is. Thanks for any help you all can give me.

 

[Kurt_Nelson]

They just look like sponges to me. Fine things to have.

 

[Zer0]

First one sponge for sure, second one looks like the hard outer shells of Spionid worms. All harmless though..

 

[bennett85]

Thanks Kurt Nelson and Zero for your help. So how big can the sponge get and what do they do if anything?

 

[Zer0]

Sponges can get pretty big, and they can spread... but in the home aquarium don't expect them to take over anything or grow to gigantic proportions. They usually just come and go as the proper nutrients for their growth present themselves.

"IF" it is a sponge, they are harmless filter feeders, feeding off whatever floats around in the water column.

In the second picture, if those are in fact spionid worms, they are also harmless. They can spread pretty quickly if there's enough food in the tank to support many of them. You will see string-like tentacles extruding from the shell at any time of the day, grabbing around for food.