This looks like some kind of sponge to me (ha, like what the heck do I know?) I noticed it growing behind some stuff and see that it's spreading over the fiji LR that it must have come in on about 6 months ago. Tell me it's no problem and I'll be happy. Notice a little tube extending from the network of light yellow filiments by the fire fish tail.
Attached files /attachments/sites/default/files/IMG_0656 - Copy.JPG
Attached files /attachments/sites/default/files/IMG_0656 - Copy.JPG