Terrifying (but tiny!) bryozoans
Images 1 and 2: Beania mirabilis (source) cc-by-nc-sa
Image 3: Electra monostachys (source) cc-by-nc-sa
The sea pig, Scotoplanes globosa — a deep-sea sea cucumber
Via Echinoblog: http://echinoblog.blogspot.com/2009/07/because-you-demanded-it-sea-pig-aka.html
Images 1 and 2: Via Wikipedia. Link 1; link 2. Lindberg, 1882, Report on the scientific results of the voyage of H.M.S. Challenger during the years 1873-76 : under the command of Captain George S. Nares, R.N., F.R.S. and Captain Frank Turle Thomson, R.N. (public domain)
image 3: (the shiny pink one — source)
Image 4: (the sinister-looking one — source)
Image 5: (the other pink one — source)
Image 6: (the toy — source)
Apparently it’s even been made into a toy by Agatsuma! Available on ebay.
Image 1: Basket stars (Gorgonocephalus) SERPENT project (img source)
“These basket stars were observed offshore Norway at the Midnattsol field. They are at the top of a ridge on the seabed at 928m depth using their branched arms for filter feeding in the strong currents.
Image 2: Basket star (Gorgonocephalus) SERPENT project (img source)
“This basket star was observed offshore Norway at the Midnattsol field at 928m depth. You can see a big close-up of this creature at http://www.serpentproject.com/magnify_gorgon.php
Image 3: Gorgonocephalus. SERPENT project (cc-by-nc-nd)
That second one has its mouth facing up — there are photos out there, but watch out — it’s nightmare fuel! (see also: Sarlacc)
Via this excellent photoessay!
(Sarlacc comparison from this post)