The recent thread on Neroli oil and its source under preshaves etc. got me interested in other things that some might believe exist but are in fact either fictional or a misunderstanding of the root of a name. To start this off, here are two more from my list.

Canola plants (as in the source of canola oil)
Naugas (the source of Naugahyde).

Add you own. To qualify we must be talking about a nonexistant physical object (plant, animal, mineral) whose existance is hypothesized due to some false identification by humans. Not a mythical or spiritual being whose existance can neither be confirmed or denied (basically I do not want this to deginerate into a discussion on theism, atheism and/or agnosticism). Let's keep it real, or at least in the realm of this world.