Chordate or cnidarian?

[martin.a]

Or, more precisely: ascidian or anemone? It is (they are) a hitchhiker on live rock. They were not visible there when the rock arrived month ago. I noticed them yesterday. They are about 10mm tall and seem to be growing. They respond to touch, response is relatively slow, not rapid like with aiptasia. After touch they slowly retract into a 'small oval-ish ball' and come back after few minutes. Rocks are from east coast of Australia.
From they way they are attached to the rock, I would risk colonial ascidian, but gosh, where is the second siphon? And the flared rim?

 

[Jay Hemdal Verified Community Expert]

Or, more precisely: ascidian or anemone? It is (they are) a hitchhiker on live rock. They were not visible there when the rock arrived month ago. I noticed them yesterday. They are about 10mm tall and seem to be growing. They respond to touch, response is relatively slow, not rapid like with aiptasia. After touch they slowly retract into a 'small oval-ish ball' and come back after few minutes. Rocks are from east coast of Australia.
From they way they are attached to the rock, I would risk colonial ascidian, but gosh, where is the second siphon? And the flared rim?

I’m not too familiar with Australian micro fauna, but this looks like some cnidarian to me.