What is this?

[tarponchik]

I've seen these only in Belize, and only at Amberhead site, where the famous white-spotted toadfish lives:

 

[Kukuisa]

It looks like red alga and more specific Pink bush alga (Wrangelia penicillata). The are common in the Caribbean.

 

[designbysue]

I believe I have actually seen a lot of that throughout the Caribbean.

 

[tarponchik]

Using the scientific name you gave, I found this image here:

This is certainly different. The stuff from Belize looks more like little red cranberries on colorless branches.

 

[designbysue]

Can you post a larger image of a close up showing the "cranberries" It's hard to see on the posted pic

Sue

 

[tarponchik]

Sorry, the quality is not too good.