White "pineapples"

[Callen]

What are the little white pineapple looking things? Several of them have popped up over the past month.

There are two of them in the photo. The one on the left is in better focus.

 

[AbsoluteFaye]

Pineapple or q-tip sponges. Harmless filter feeders.

 

[HN1]

Pineapple or q-tip sponges. Harmless filter feeders.

Agreed. IME, they tend to "come and go" as the tank matures.

 

[Callen]

Would they be a sign that my tank is starting to mature? That would be nice!

 

[HN1]

They are a sign that you have a healthy, maturing system and should keep doing what you're doing. IMO