Oh yea, this is going in one of my campaigns. 4 ft long and eats metal. What's not to love?
Giant Sea Worm
MV: 9/18 swimming
AT: 1 bite (1d6)
SP: Upon successful attack, target must save against the paralyzing/numbing affect of the worm's bristles. Failure means a numbing or loss of use of a limb. This effect is cumulative. It is up to the DM on the specific location or effect (suggestions include cumulative -1 to hit/AC, -10' movement, can attack only every other round, and so on..).
If the creature scores a critical (natural 20) or an attacker fumbles (natural 1), then an effect could be that the worm ate some of the metal of the attacker's weapon or armor - DM's choice.