Please help me ID

[JurisHP]

Just discovered about 30 of these next to eachother in a remote part of the tank near some rock. Any ideas as to what they are and should I remove them?

 

[Sniperhank]

It's really hard to see with the actinics going. Can you get the whites on so we can see things more clearly for a better ID? They look like sponges, but it is really hard to tell.