Model, Texture, Rig, Animate a Worm in Blender ... and import it into Unity
Blender is a powerful 3D modelling tool and it's free so it's a great choice for indie game developers starting out.
You might well be feeling a bit overwhelmed by how much there is to learn to model something, animate it and bring it into Unity 3D to make an interesting game asset.
As usual, there's about 5 ways to do any one thing in Unity so it can be difficult to know how to proceed. For instance when it comes to animation in the Unity engine, root motion is what makes the character move when it does its movement animation. You can drive this from code or you can drive it from the animation itself. It's a choice and there are pros and cons for both.
The document below is about 40 pages long with step-by-step instructions on how to create a brand new model - a worm in this example - and takes you through doing all the necessary steps to import the animated worm into Unity and use Unity's Mecanim tool to use the animation clips in the game.