Clear mystery critter

[Hemmbone20]

What are these clear jelly like things growing on my TBS live rock rubble?

 

[ISpeakForTheSeas]

Tunicates - harmless filter-feeders. Feeding some phyto (particularly Isochrysis, Rhodomonas, or a blend with one or both) is a good place to start if you want to try and help them do well in your tank.