Pearling

Yes, they can.
Pearling is not an indicator of happy plants as they can pearl for many reasons. A water change, lowering water conductivity, over fertilizing by previously unavailable nutrient, etc., ...

Edward

Pearling can be generally considered as evidence of photosynthesis. In a significantly P limited tank you can still observe pearling but show very little growth. Rodger Miller put forth an theory of the biochemistry involved in a previous thread titled jungermania; look it up if you dare. In this particular situation, pearling is strong during a nutrient shortage.
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Jeff