What is this?

[ondy6611]

The purple stuff on my silicone anemone

 

[Fish Fan]

The purple stuff on my silicone anemone

#reefsquad

I'm not sure what that is; following to learn ;-)

 

[tbrown]

It's algae. Almost looks like freshwater Black Beard. It's probably the beginning stages of GHA (green hair algae).

 

[EnterName]

I second algae... If it's not really green under neutral light, it might be covered in diatoms which cause a brown-ish discoloration. They frequently attach to green algae and cause this.

 

[Mr. Mojo Rising]

I use these things in my seahorse tank, algae will always grow on fake plants and corals. You will have to resign yourself to cleaning it monthly if you want to keep it clean.

 

[Fish Fan]

Ha! I didn't see that this is a 'silicon' animal, I thought it was real

 

[Rocks reef]

The purple stuff on my silicone anemone

Looks like algae tufts to me.
Are you able to scrape it off? You could soak the silicone thing in a 50/50 mix of peroxide and RO. It’ll kill the algae and the residual, if any, won’t hurt the tank