Medieval siege weapon

[Norseman]

There's this one weapon whose name I cannot for the life of me remember, basically from the front you have a board like so:

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|ooooooooooooo|
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The little o's are the holes in the board, and a big spear / bolt comes flying out of each of them. They were used as a defensive weapon in castles, very handy I suppose. I think they used some kind of crossbow / arcuballista mechanism to launch the bolts / spears (they were huge).

The problem is that I can't remember the name of it, I was hoping you could refresh my memory, and better yet link me to a picture and some descriptions.

[Cynical Cat]

I know of a smaller version called a springboard that launched a hail of darts, but that's all that's coming up at the moment.