Does anyone know what this hitchhiker is?

120 gallon tank just finished cycling with 150 pounds of live rock from someone else's 6+ year old reef setup.


Looks like some sort of anemone to me.

 

Oh, it is about as big around as a dime, maybe a hair less than that.

 

So kill it then?

 

This is on a smallish rock that can be easily removed without disrupting any other rock work. Now to figure out the best way to kill it. I don't have kalk. Even IF it is something else, I would rather add an anemone when *I* want to and know exactly what it is.

 

Well, since I couldn't tell for sure, and since it was already spreading on the same rock (there were 3 on the same rock since I first posted. The one in the picture and 2 tiny ones), I killed them. I took the whole rock out, and let it sit in boiling hot water. They fell off. I left the rock in the hot water overnight, then today lightly brushed the rock and put it back into hot water. Tomorrow I will take the rock out of the water and let it fully dry out for a couple of weeks just to be sure. The rock is obviously dead, but it will grow back after a while, just hopefully without any hitchhikers.

 

Well, if the one just appeared one day on the rock out front (shown in the picture), then it came from some other rock and I very well could have more. It either started reproducing or something because there were tiny ones that showed up on that same rock. My fear was that it would be a pest and take over the tank. If it had just stayed that one since anemone, then I would have waited a little longer to take action, but when I saw others I was afraid of a population explosion.