Wierd growth & clam on live rock? Questions with Pics...

[GatorDrew]

Alright,

So I'm sitting at the table and I notice a couple of things. First, there's some weird purple/black thing. I originally think nothing of it, but then I look again and he's moving. I glance over to the other side of a tank to look at some new live rock I got... and notice that something was moving on it. After further investigation, it looks like its a clam! The only thing though... it looks like he's upside down. He started opening up from the bottom (does that make and sense?) Below are some pictures...

Purple/Black thing

The clam.

The Tank

Thanks for your time and answers! I really appreciate it!

 

[Fluff]

The purple and black thing is a chiton. Nice critter to have. It's an algae grazer. The clam is a turkey wing clam and that's it's normal position.

I'm moving this to the sw ID section.