Moray Snail

Here's one of the critters living in the partially-flooded 3rd level of the dungeon.  A question for my readers:  did somebody already make a monster like this?  I think it's all me, but I've read a lot D&D related material, so it's always possible that I picked it up somewhere else subconsciously...

Moray Snail
No. Enc: 1 (1)
Alignment: Chaotic
Movement: 60' (20')
Armor Class: 2
Hit Dice: 5
Attacks: 1
Damage: 1d12
Save: F5
Morale: 10
Hoard Class: V plus shell
XP: 500

Moray snails are giant eels with six crab-like legs, living inside intricate shells. The eel head may strike up to 10’ away from the shell, withdrawing back inside after a bite. If the head and neck is somehow prevented from withdrawing, it has an effective AC of 8.

The bite of a moray snail is venomous, and its victims must save vs. poison or be paralyzed for 1d4 turns.

The shell of a full-grown moray snail is 5’ in diameter, and is banded with a rainbow of bright colors, overlaid with iridescent arabesques.  Undamaged, it is worth 500 gp to a collector.

When necessary, moray snails may scuttle about on their crab-like legs, but they prefer to wait in ambush for prey – easily done in the dark, but any party with a light source should have no problem spotting the moray snail’s brightly colored shell.