Spawn body ideas

Ok, I have a rough design for the maw and arms of my Spawn drawn up, but as such I was still lost designing the main body. Consulting the staff at my local Games-Workshop, it seems the Tzeentch daemon designs come partly from sea creatures (e.g Screamers why didn't I think of that?). So on their advice I've been searching the internet for strange sea creatures for ideas. Here's a few I've found:

Body wise, it's hard to see any shell used as the Spawn has no armour, but the design idea is good. Also, lots of legs seems the way to go as well.

Possibly a good tail idea, but it's the colour scheme that seems quite Tzeentch and would go well for the body.