Clam biology question

[Palmer]

Yeah I am familiar with the small tentacles around the in siphon just not the longer thing coming out the out siphon. Was doing some reading and I am wondering if it isnt clam poop. It is supposed to contain zooxanthellae and mucous and usually brown/red. This is blue/purple but since that is the colour of the mantle maybe it is still waste.....

I am trying to post a picture from another site. There is no way I could get it on my camera, I am horrible with tank pics.