I am not a zoologist but this is a cool animal. :)

Hello,

this look like a Nudibranch egg mass. but need to be checked with a closer look at its content. 

I would join to the assumption this is an egg mass of a nudibranch gastropod. However, eggs themselves are not discernible on the picture.

Dear colleagues, thank you so much for your cooperation.

Really looks like a Nudibranch egg mass.

I think it is a Nudibranch egg mass

It does indeed resemble the egg mass from a mollusk.

Dear all, I am not able to see tiny eggs inside this transparent spaghetti. Thus I have my doutbs that this is the eg-mass of an opistobranch. I am neither able to see any sort of longitudinal tubular structures inside this spaghetti, so it doesn't seem to be a Nemertine worm, although this cannot be excluded. But maybe it could it be a piece of an acontium of a sea anemone or the tentacles of some sedentary Polychaeta living inside tubes or galleries in the substratum?

I think it is a egg mass. Probably is the egg mass of a Nudibranch.

looking like egg mass of a nudibranch gastropod