okay.. here's a saltwater creature...
Blanket
Octopus

normally, it moves around without its "cape" but when
frightened, instead of squirting ink, it unfurls that huge webbing
which makes it look a lot bigger and intimidates its enemies...
you can see what it looks like when it opens up...
clicky => here
another thing which is amazing is that it is immune to the
stings of the jellyfish the Portuguese Man'o-war... it uses that to
its advantage by ripping the tentacles off the jellyfish and uses
it as a weapon...
another thing is that the male is about the size of a walnut
(the female is about 1 metre... it drifts around and when it meets
a female, it rips a tentacle off and gives it to the female which
uses that to fertilise its eggs.. the male then drifts off and
dies
some of these weird sea creatures have the most bizarre of
designs.