New hitchhiker. What is this?

[Sycamoron]

Noticed this guy a few weeks after adding some live rock. Good or bad?

 

[Piscans]

lightbulb anenome, could be a problem when it gets like 4" across if you have sensitive coral or small fish that arent very smart (one of mine ate a dead molly whole). i only have kenya tree and palys so i have no problems with mine.

 

[Sycamoron]

lightbulb anenome, could be a problem when it gets like 4" across if you have sensitive coral or small fish that arent very smart (one of mine ate a dead molly whole). i only have kenya tree and palys so i have no problems with mine.

Thanks for the ID. It's in a safe spot, so I'll just keep an eye on it as it grows and/or wanders.