Please help identify black stationary slug like thing

[nweiher7]

Please help , what are these black slug looking things ? They don’t move . They are smooth , and raised up . I touched them with my grabber tool today , while cleaning the tank . My tank has been pretty ignored , for about 3 months . I’ve had it about 7 years , and never seen anything Ike this . No new tank additions in 3 years , or more possibly . When you shine a light on them at night there are kinda holes that show up and almost glisten ? They are stationary , and didn’t react to me touching them earlier . I’ve been bad with water changes , so I know my water isn’t great . Just some info you might need to help identify . Ty

 

[nweiher7]

Here’s the best video I could get

 

[ISpeakForTheSeas]

Welcome to Reef2Reef and sorry for the slow response!

It's hard to say for sure from the video, but between the video and your description, it's most likely either a sponge or a colonial tunicate of some kind (though I'm leaning toward sponge).

 

[nweiher7]

Thank you , that's what I’m leaning toward also. I appreciate your response !