What is this on my Acan?

[Regalcinema]

Hello!
Recently I have noticed something coming out of 2 of the heads on my Acan. Almost looks like a piece of string coming out of the mouth. Just curious as to what they could be?
Any help would be appreciated
Thank you!

 

[KK's Reef]

If it's dark brown and stringy, It's pooping.

 

[Regalcinema]

If it's dark brown and stringy, It's pooping.

Hey now that you mention it I think you could be right! Thanks for the input!

 

[sfin52]

It's taking a duce