ID help please

[TheWB]

I’m not sure that these are critters or hitchhikers but I’m hoping this is the right place to ask.

There are white tubular looking growths hanging from the bottom of the black egg crate under my rockwork and on the rock itself. I’ve never seen this before. Can anyone help with an ID? Thanks.

 

[P-Dub]

Likely sponges or tube worms. Normal at any rate.

 

[TheWB]

Likely sponges or tube worms. Normal at any rate.

Thanks

 

[Proteus Meep]

Clathrina Sponges have that growth form