Not a plant, I think it is a pink gorgonian (Paramuricea or the kind)

Although I am not a marine biologist (zoologist), it looks like a soft coral (Gorgonian).

I would have to agree with the other suggestions.  It looks very like a gorgonian.  there are many species of these and if you were able to tell where it was found there is a strong possibility it could be identified to genus and perhaps species.  Indeed if the depth it was found at could be indicated this may also assist in an identification. 

One more on Gorgonian!

Gorgonian!

Agree not an algae at all, looks really like a Gorgonian

Definitely a gorgonian!

My field of expertise are freshwater macrophytes; nevertheless I would say it looks like a Gorgonian.

Certainly not an alga (some kind of colonial invertebrate, but this is not my area and I am not able to say what exactly).  

We need microscopic view.

Sorry, I have never come across through this kind of specimwen

Definitely a Gorgonian soft coral- not an alga

It looks like a gorgonian, but it would be useful to have photos of sections under the microscope ....

It is a gorgonian (see for example paramuricea clavata. But as an example, I do not if it is a Paramuricea)

Definitely a gorgonian, where was it found?

It looks like a gorgonian

Is this aquatic from sea?

I would say it is coral refugium.

but am not sure, never see it before

Gorgonian

Yes, it look like gorgonian...

Gorgonian,the Indonesian named is Akar Bahar. Thx

I think it's a gorgonian.

At first sight, I'd also say gorgonian.

However, wouldn't anyone consider it may be a sponge growing over a gorgonian squeleton or even a tree branch?

It should be a Gorgonian.

i think it should be  a gorgonian

I asked a specialist. He and I agree that it is a gorgonian. You can see the octocoral polyps being retracted. It is not in good condition, because the soft tissue becomes detached from the axis. To be sure about its identity, you should analyse its sclerites.  

I do not deny that this might be a gorgonian, but my first impression was a bryozoan (Ctenostomata), sitting on a brown algae. Higher magnification would be useful...

I´m not sure about the specie but I think the same as Ernest Schockaert. I think it could be a bryozoan.

I don´t know the species but it is a Gorgonacea.The position systematic is following:

Phyllum Cnidaria

Subphylum Anthozoaria

Class Anthozoa

Subclass Octocorallia(=Alcyonaria)

Order Gorgonacea

This is a gorogonian, as Zamponi has said...they are subtotal. 

That's subtidal.....my spell check took over. 

You need a taxonomic key for your area, or contact an expert. I saw two.gorogonian papers lately, one by Buhl-Mortensen, and another by H.R. Lasker. 

This is a gorgonian (sea fan) of the Genus ECHINOGORGIA...The image is upside down. A common species in the Gulf of Mannar (specifically to Tuticorin, Vembar, Pamban and Rameswaram areas). Often found as by catch from bottom set gill nets called NANDU VALAI (Crab nets).

I confirmed this species with an expert and it is LEPTOGORGIA sp. You can contact Dr. Yogesh Kumar of ZSI for further details at - [email protected]

all the best