Weird pattern cut open on pink frogspawn?

[Andresnyc93]

I’ve noticed this weird cut pattern that closes and opens every now and then on my frogspawn. All other euphyllia is perfectly normal and they’ve all been thriving recently. Tank parameters are: salinity- 1.025
Ph- 8.2
Calcium 420
Alk 9.0
Mag 1400
Nitrates 10
Phos .01
Par 150
Frogspawn doesn’t look like this always just when I took picture

 

[Andresnyc93]

Bump

 

[Shirak]

some sort of clam on the outside?