What's riding on my Trochus?

[RickLRMS]

This video is from my Invert Quarantine Tank. I'm new to this, so far the only functional tank is the IQT. Wondering if the "tube" on the shell (lower part of video) is a vermedit snail and also wondering what's pulsing on the shell (upper part of video). Sorry for the "verticalness" of the video. Don't tell my wife, who I tell to never take a vertical video.

 

[Hadla]

Aww I can’t help you but I love seeing snails with their own little pets XD

 

[Kristopher Conlin]

It's a barnacle. Harmless filter feeder.