Please, help ID these slug-textured spots on just received live rock

[Obriy]

I've just received very nice live rock rubble from KP Aquatics. Can you, please, help me with identifying those? The thing on the first photo is grey-green in appearance and hard on touch. The other two photos show something that is black and soft/moist on touch.
Do I keep them, or do I toss away these three pieces of rubble just in case?

 

[tzabor10]

They look like tunicates. Pretty cool in my opinion. I have had success keeping them. Where is your live rock from?

 

[Obriy]

The rock is from KP Aquatics.
Will tunicates survive in aquarium, or will they die?

 

[tzabor10]

The rock is from KP Aquatics.
Will tunicates survive in aquarium, or will they die?

I have successfully kept many but am dosing silicates from brightwell. Spongexcel is good for keeping sponges but you need to test for silicates Salifert has a test kit for this.

 

[Obriy]

I have successfully kept many but am dosing silicates from brightwell. Spongexcel is good for keeping sponges but you need to test for silicates Salifert has a test kit for this.

What are the reasons to keep tunicates in an aquarium? Definitely not aesthetics, right?...

 

[tzabor10]

What are the reasons to keep tunicates in an aquarium? Definitely not aesthetics, right?...

I like them. Reef keeping is a somewhat exotic pet hobby. Tunicates are the most distant chordate relatives. I enjoy seeing variety in my tanks