Hitchhiker ID, please!

[Crazed]

There's a strange... growth that's been on my rock since day one. Originally, I thought it was a dead sponge, since it's white and seems semi-squishy when I touch it, and it's definitely sessile; it hasn't moved at all. But, it's been around for almost 2 months now without any change in appearance, so I'm wondering if this thing is still alive.

I originally left them on the rock when I pre-cured them, since I was actually worried about the rock being too clean, and I thought a dying/dead creature would be a decent ammonia source.

There's 3 of them (that I can see) on my one rock, which was from Fiji I believe. This one pretty much had the most life on it, compared to my other rocks; grass algae, bubble algae, worms, probably my Stomatella snail, etc. Can anyone help my identify these things and if I need to get rid of them? Thanks!

Also, there's another hitchhiker I just found. I don't recall seeing this before; if it was on the rock originally, it's grown a lot since I first put it in. It's very small; smaller than the other organism. There's something that looks similar on the top of the rock too.

Could it be a feather duster? I used a baster to spray some water at it and the little tentacles retracted into the tube.

 

[Nihoa]

they look like tunicates or sea squirts. see the two little mouths on the one pictured at the bottom? harmless filter feeders.

 

[Cozmo4]

Looks like a harmless, filter feeder pineapple sponge.

 

[Crazed]

Thanks for the opinions, guys. I'm leaning towards the sponge option; for the one on the top, at least, I can see a spongey pattern that didn't quite get caught by the camera. Although the more I look at it, maybe the last picture is a different life form, maybe the turnicate Nihoa mentioned?

Is there any way I can tell if these guys are still alive? I'm glad to hear they're harmless, though.

 

[Ohiomom]

+1 on the sponge..no worries..if it dies it will just disappear..

 

[Crazed]

Could I get an ID on this thing too?

I don't recall seeing this before; if it was on the rock originally, it's grown a lot since I first put it in. It's very small; smaller than the other organism. There's something that looks similar on the top of the rock too.

Could it be a feather duster? I used a baster to spray some water at it and the little tentacles retracted into the tubes.

Thanks!

 

[Rich D]

do the sponge things have transparent spine-like things sticking out of the tips? most pineapples have these little transparent feather things.

 

[jdieck]

IMO they are not pineapples but they look like sponges to me. I have several of them. They are usually white with green spots throughout and their consistency when touched is "spongy" if you know what I mean. They are harmless even if they die.
The other organism is difficult to asses as the tentacles you mention are not clear in the picture. My initial impression was for a mushroom or a palythoa.

 

[Ohiomom]

they are syconoid sponges which I think are in the same family as the pineapple ones. But seriously no worries on them. As for the second picture, ?, any chance of a better picture..try the macro setting on the camera if possible..little flower icon on the camera..

 

[CoachOJ]

The 1st pics are sponges. The last pic looks like hydroids but can't really tell for sure from the pic

 

[Crazed]

I'm sorry, but I don't think I can get a better pic on the second one. =/ It's quite small, and even with a Nikon D80 I can't get it clearer.

Thanks for the expertise though, everyone. As long as I know they're not harmful, that satisfies me.

 

[jbryant]

The other coral is a leather coral I think they are called cabage leather. They are pretty hardy judging from the ones I have. Hope that helps