The entire contents of the various racks and tanks belonging to The Collector (Benicio Del Toro) will take some serious time (and likely a home video release) to fully examine, since most objects are only seen for split seconds - with some early rumored collectibles debunked by other viewers.
What does stand out among the various objects is the rather sizable tank containing what looks to be a large object of both organic and mechanical design. It's been suggested that the item is in fact Adam Warlock's famous cocoon, from which the troubled man was reborn with a new purpose, and an irrevocable link to the Soul Gem - set to play a major part in Marvel's Cinematic Universe.
So far, it's hard to confirm whether the cocoon is in fact Warlock's, since it isn't visible in its entirety. But given Joss Whedon's affection for the character, we wouldn't be surprised to see Warlock emerge in the near future.