Is this a threat?

[Joe BBC]

Not sure if pic uploaded. New at this.

View attachment 20190225_165428 (1).jpg

 

[Brad Miller]

Pineapple sponge, harmless

 

[Lovemyreef2015]

Agree ^^ good filter feeder

 

[Joe BBC]

It has what looks like a tail?

 

[reef lover]

Thats actually its mouth ...so to speak...filtering parts

 

[Joe BBC]

Thank you. Can they get out of control? I will watch for them.

 

[Brad Miller]

If he's on a rock his "tail" will be outward towards you, to filter the water
And yes, Their population could get exponential but they have eventually die off