The Creature mod is a Minecraft mod is made by dsm1891 on Thecreaturehub forums. (See here.)
What the mod is about.
This mod adds more mobs to Minecraft, these mobs include Seamus, Kootra and Nova. These mobs spawn in any Minecraft biome, and have an evil counterpart to them, which only spawn in the Nether. It says on the forum post of this mod that a rare Nova mob spawns which you can infact ride. From the looks of it the creator of this mod has intended to add the other 4 creatures, and the 3 former creatures, but it seems he/she hasn't got around to doing so. Creature mod made a return in 2012 by a different person but no Creature found it and yet again had stopped at V 4.7.