I need to know

[Antonio1984a]

Can anyone tell me what is this yellow thing in my tank

 

[Squishie89]

A picture would help

 

[Antonio1984a]

Haha haha sorry I forgot

 

[Antonio1984a]

I don't know what this is

 

[Antonio1984a]

It looks spongy

 

[davocean]

Agree, sponge, harmless

 

[ReeferEric]

Yup, sponge. It's fine but you can remove it if you don't like it. Its a filter feeder.