Clove polyp head disappear/retract...

[Patx]

In the past (other tank, other world) i had a cherub angelfish.
Some head of my clove polyp was missing here and there...
I was attributing this to my cherub...

So now new tank, new world... no cherub...
But still... same problem...
Ok not a big deal but why ?
Flow ?

See the "white head" on your left ?
Any idea ?

Clown
Silver bellly
Royal G.
Tail spot blenny
Diamond goby
Flame hawkfish
1x 10 years old hermit scarlet ?

 

[Reefing Madness]