possible clam?? and something else...

[elise]

Well i was at the book store yesterday and i was looking at this saltwater encyclopedia book and i stumbled across a clam type thing that looks similar to what came on my Liverock a few weeks ago.. i didnt pay much attention to it because i thought it was dead.. [today i saw it pinch its mouth down - it was only open 1milimeter at the most, but i still saw it move lol]

I know i could always go back to the book store to see what it is.
but do any of you have any idea what it is? is it just a clam?
I searched for clams and scallops but none of them looked like this.

in the book it said they were rare.. but i dont know..
(its the 2nd pic)
___________
The first pic has the clam thing And another weird jelly looking creature that came on the rock. I know its not dead, because the tips are starting to look better - it was in rough shape when it arrived. Anyone have any idea what it is?
(dont mind the other pests on that rock)

 

[jackdp]

The bottom pic is a spiny or thorny oyster...filter feeder, fairly hardy. Do a search in google images to see some more pics. I had one in my tank until a vacation evaporation problem took it out...and the top pic I can't really make out...sorry.

 

[elise]

cool thanks!

 

[ReefGuru]

Second the spiny/thorny oyster. The first pick, by my guess is either a porifora (sponge) or some sort of an encrusting cniderian. Look at it closely. If it has polyps then its a cniderean, if it only has pores, then its probably a sponge. However, I have noticed that you have a lot of aptesia, and I would suggest taking swift and decisive action to erradicate them.

Andrej