What are these white tubes growing?

[xycose]

What are these white tubes growing all over my rock? I have two rocks like this.

https://imgur.com/a/IoP6L

 

[Sugar Magnolia]

Harmless sponge growth.

 

[Rover88]

What are these white tubes growing all over my rock? I have two rocks like this.

https://imgur.com/a/IoP6L

I just got those myself the other week As Sugar Magnolia said, harmless sponges.

You also might find little ones that are oval-ish with a brush sticking out the top. Those ones are Sycans (Pineapple Sponges).

I find it interesting yours are directly in the open. All of my sponges only came about underneath the tops of the caves I have, none on my rock in the open.

 

[xycose]

Thanks for the help! Harmless is what I was hoping to hear.

 

[totoro]

+1 on being harmless. I wouldn't worry about those sponges.