How big are Baby Montipora Eating Nudibranch's? Are they Invisible? I see White Spots

How big are Baby Montipora Eating Nudibranch's?



Are they Invisible?



I see White Spots around Some Edges of Montipora but I do not see any Nudi's.



I have seen bigger ones so I know what they look like but do not see any on the White Areas where the Montipora was Eaten.



I even tried to use a Magnifying Glass and do not see any.



So how big are Newly Hatched Babies and How Big can Adults get?