Help ID: Tuber like growth on rock

[AggieLuke]

Any idea what these tuber like growths are on my rock? They start out looking like pimples and get longer in areas where cuc can't get them. Seem to be able to grow with or without light.

 

[Sophie"s mom]

Not sure what you are talking about, any way you can circle it, or have an arrow pointing at it.

 

[DaJMasta]

Are they dark green and shiny? Could be bubble algae.

 

[AggieLuke]

Top circle is when they are longer because the cuc is not getting to them. Bottom circle is the pimple like version that they start of as....tuber or finger like.

 

[AggieLuke]

Are they dark green and shiny? Could be bubble algae.

Its like finger or tuber like....not algae like at all.