It seems like these are nocturnal and the white worm like creature seems to retract during the day and come out at night and scour the rock that it’s anchored to. It also has 2 arms or tentacles that come out from the base. I haven’t been able to get a really good picture of the black one since it seems to shy away from the light. It’s the black thing on the right of the second picture. It seems to have some sort of antenna or multiple arms or something coming from the front and it seems like it’s all black. It moved pretty quickly away from the light after it exposed itself briefly.