Blue Button Jelly (Not actually Jellyfish)

No... its not a real button 

This "button" spins it's tentacles around in a very interesting way. Not only does this guy look cool but he is also blue (I like the color blue). It's pretty much the size of a button which is probably why it has it's name. More info below. 

This is in a small plastic cup (very tiny jelly)

Tentacles are wired 

More wired tentacles and something else

This looks cool

The blue button jelly (scientific name porpita porpita), is not actually a jellyfish.  Technically, it is a hydroid, which is also in the class cnidaria with jellyfishes.  The blue button jelly is typically one inch in diameter.  At its center, it has a hard golden brown gas “float.”  Surrounding this core are several hydroids, which are similar in structure and purpose to jellyfish tentacles.  Like many jellyfish, these hydroids have nematocysts (stinging cells).  The blue button is found most commonly in the Gulf of Mexico, Mediterranean Sea, and waters surrounding New Zealand, Europe, and the southern United States.  In these waters, the jelly floats near the surface.  The primary diet of the blue button is plankton. 

http://marinelife.about.com/od/invertebrates/p/Blue-button-jelly-profile.htm

Authored by Josh Ng