Any idea what's on the other end of this?

[Jabru]

Anybody have a clue what this long black tube thing is living in my live rock? Saw a clear looking one aswell

 

[blaxsun]

I am honestly not sure what I'm looking at,

 

[vetteguy53081]

Likely some sort of tube worm - vermetid or similar. Best is to get under it with an old credit card or scraper and lift it and discard