Description: I came up with a way to make a good crawly thing that is completely posable. I modeled this creature after the face hugger in Alien but this is much smaller. You can use this approach to make all kinds of small crawly things.
Using some pliers, I cut and bend some coat hanger wire to the desired size and shape. I went to a sports supply store and bought some rubber fishing lure worms (there are all different kinds and most are cheap). I needed one kind for the legs and one for the tail. With a little patients, I pushed the wire lengthwise through the worm. Be gentle as the worms are rather soft. Leave a bit of the wire sticking out.
Did the same thing for the tail with a fatter worm.
I used some Sculpey (a plastic clay available at any art shop) to make the body (poking holes in it for the wires). After baking and painting the body, I used clear bathroom caulk to glue the legs and tail on. Done. For some of the legs, I used two separate wires so that they can bend freely at the joints.
To animate the creature, I used a mini version of a flying crank ghost using a small disko-ball motor I bought for a few bucks at cheaplights.com, fishing line and some simple hardware. Please look at the flying crank ghost link to understand the mechanism here but this is easier to put together than the ghost. I cut a 3" piece of wood and attached it to the motor with some wire and put a bolt through it so that the bolt stood up about one inch. I tied the fishing line to a washer and feed the line down through holes in the top of the tank (the creature is below in the tank). You may notice the copper tubes the fishing line is passing through. Those are copper crimp connectors I got from Home Depot (electronics isle) for a few pennies. I used those so that the line would not catch on any splinters from the hole drilled in the hard board.