What are these?

[deetu]

Wasn't sure where I could ask this. Can someone tell me what these are and if they are good.
They are about 1/4 inch and smaller, attached to the rock, soft and do not retract when touched.
I saw one in display but most are in my in tank filter where it is dark.
Looking up hitchhikers what looks closest is sponge... possibly pineapple?
Please please please let them be good

 

[Mrx7899x]

I cant see the picture but sounds like a sponge

 

[diana a]

+1

 

[deetu]

 

[meherbas]

They look like pineapple sponges

 

[diana a]

Yes pineapple sponges.

 

[deetu]

whew! thank you