Little polyps

What are these? Theres a colony of about 50 of them on one of my rocks. They have 8 "tenticles" and are very small. They don't look like aptasia...already dealt with an outbreak of that.
What do you think these little "polyps" are?

 

You have a nice patch of hydroids my friend (hydroid Myrionema) ---

Definitely a nuisance and hard to get rid of.

Not much of a problem for soft corals, can sting sps.

I have learned to live with mine. - They stay in patches (colonies) and spread very slowly, at least in my tank.

I have seen red legged hermits mowing them on occasion...pull out rock and scrape off is all else I know how to do. :-/

 

I agree with OMARD if they are hydroids "GET RID OF THEM".
I had them in my 10 gallon and someone told me to get rid of
them a 1.5 months ago and I didn't.

November 4th


in that short span of time they spread everywhere. The
original colony had completely covered the rock it was
on plus spread to other rocks in the tank! I tried to pull
them off but ended up tossing the rock out. Unfortunately
I did not take a picture before I tossed it but you can see
how much the spread from the small little clump in the
picture above!

December 4th - the brown topped rock on the left.



But from you description "They have 8 tentacles and are very
small" they sound like an octocoral, I have a colony of about
30 little brown polyps on one of my live rocks. I cant really tell
in your photo, here is what mine look like.



This is a bigger clump I bought of something similar

If they look like this leave them alone they are fine to keep
and will eventually cover the rock.

Hope this helps.

 

Hydroids in my tank...

​

Notice how zoa's grow amonst them just fine...:-/

 

I'm still not sure from the pics you guys posted...but it's definately helping. (easier to see what you're talking about) My battery is dead in my camera...charging it now....I'll take a better pics tomorrow and post it up...thanx for all your help

 

Hydrozoans
Good info on hydrozoans!

 

I'm not 100% sure but it seems that if you are talking about the animal in question containing 8 tentacles, then we may be talking about a type of octocoral or soft coral!
Based on my observations studying many forms of hydroids, they seem to have four or six or 12 or more tentacles. The brown pom-poms(myrionema) hydroids contain 12 or more tentacles and are a few centimeters in length.
from your picture they do look like hydroids, but the 8 tentacles is stumping me. Maybe a closer and better picture will help to accurately depict what you actually have!
Just my 2 cents worth of maybe a highly inaccurate answer...

 

Hydroids(very vague and commonly misused description) can have any number of tentacles just like jellyfish since that is what 99% of hydrozoans grow up to be. There is over 2700 known species. I would be extremely concerned with them considering there has been a lot of austrailian corals hit the market the past couple of years. The box jellyfish is the most deadliest and commonly found in australia, it starts its life as a hydroid just like all other jellyfish.

Another thing, this may or may not relate to this... Its become common practice to call all of them hydroids since they look similar at that stage but there is actually 3 different type thats fall under the phylum cnidaria. Everyone has 2 stages in their life cycle, polyp and medusa. Medusa being the the actual jellyfish and polyp which is what we typically see in an aquarium (Ive removed a few hundred of the medusa's out of one of my tanks recently).

Hydrozoans-Man-O-War being a common type we should know. They can reach up to 90 feet if I remember correctly.

Scyphozoans-Cassiopeia being the most common seen in the aquarium trade.

Cubozoans- The Box jellyfish belongs to this family.

 

I found mine when I was cleaning some equipment and something stung me. I took a couple of pics of them so if anything happened to me, somebody could show a pic of them. As a result I have done a lot research on jellyfish, reading everything I can find on them from some post on a forum to research studies from UC Berkley.

here is a pic of the ones I pulled out

 

well...it's been a while and the things growing died off the rock...then sprouted on another rock and have covered it.
Here is a better pic...googling looked more like octocoral...but they have totally covered the rock they are on now and are starting to spread to the adjoining rocks.
Hope this pic helps ID them.

octocoral or hydroid? - 3reef Photos

thanx for all the help.