Any ideas on what this is

[Clayton122]

 

[Flippers4pups]

I have no clue! #reefsquad

 

[Mr_Knightley]

Look up Padina algae, I'm almost positive that is what it is. Non invasive an awesome looking.

 

[Zagecko]

Perhaps a molusk, coral, barnacle, eggsack, larvae, or anemone

 

[Crabs McJones]

They're eggs, and its driving me nuts I can't remember what lays them off to the web I go! ;Bookworm@kj

 

[saltyhog]

They kind of look like some whelk eggs that I had recently but they are much larger! @KJ

 

[ScottR]

They kind of look like some whelk eggs that I had recently but they are much larger! @KJ

I think you nailed it. Seen this before. Whelk egg case.

 

[KJ]

They kind of look like some whelk eggs that I had recently

Agree on Whelk eggs.