anatomy

I was watching my nassarius snails move when I put food in the tank, and it looks like some of them have a browish yellow flake like thing attached to their tails.. is that normal anatomy? Or is that a flatworm or other parasite and how Do I go about it? Thanks fellas I attached videos

I just wanted to share this odd polyp that my Bernardpora has. I guess this is where my coral anatomy knowledge breaks down. The “tentacle” (extension that ends in a polyp) of a Goniopora or Bernardpora is a single polyp? What is the name for the base of the polyp? Anyways, this colony has...

Today I noticed slime oozing from these spiked protrusions on my Caulastraea. They seem to extend and retract. I can’t seem to find them on anatomy diagrams and such. What are these protrusions?