Pest on frogspawn?

[Sandroni]

After the lights went out a few minutes ago I noticed this nudi looking thing popped up. Anyone know if this is a pest or maybe just the skeleton?

 

[Sandroni]

its a little white thing in the front center, if u zoom in you can see it better.

 

[Mike&Terry]

I have never heard of euphyllia-eating nudibranchs - just flatworms. Would need a clearer pic, but most likely mesenterial filaments.