From which animal is this derived?
That's the gladius (also known as pen) of a cephalopod, probably a squid. The gladius is an internal remnant of the originally external shell of cephalopods.

According to University of California Museum of Paleontology:


  Members of the Coleoidea are probably the best known of the Cephalopoda, as this group contains the squids (Teuthoidea) and octopuses (Octopoda) [...] The majority of coleoids are squid species, and most of these animals are torpedo-shaped, fast moving, and have a thin, flexible internal shell called a pen.


And according to the Tree of Life project:


  Other cephalopods have other types of shell remnants. The gladius lies within a sac, the shell sac, which secretes it and to which various muscles attach. The gladius has a variety of shapes and thicknesses, is composed mostly of chitin and is located in the dorsal midline and generally extends the full length of the mantle. 


Here is one similar to yours:



Sources: 


http://www.ucmp.berkeley.edu/taxa/inverts/mollusca/cephalopoda.php
http://tolweb.org/accessory/Cephalopod_Gladius_Terminology?acc_id=1955