Should I remove these? They do scrape off with "aquarium spatula"

[Debramb]

 

[Debramb]

New to posting. These have to be a kind of hard tubed worm, as they cast thready webs in water. Tanks been up since '89, LR about 20 yrs, tons of pods on about 50 + lbs of rock. Thx to any and all that answer and please know I feel like I'm back in school, soaking in you're kind responses to all. Debra

 

[Debramb]

Sorry, 2 months ago switched from all inclosed system w/drip trays to 100 G w/sump, but these things have been growing for years!

 

[TheEngineer]

Vermetid snails. Not harmful but they annoy some people. You can cover the top of the tubes with super glue.