weird marin rear suspension thingamabob

i picked up a 2001? european model Marin Redwoods hybrid (not the american model with the same name) that has a very unusual rear suspension. i've taken it to 2 lbs's and nobody has ever seen one like it before. i don't have a photo, so i'll have to rely on my limited powers of description. it consists of a fully-enclosed barrel-shaped doohicky welded onto the top tube and attached to the back forks. it's about 3 inches side-to-side and about 2 inches in diameter. there is no spring or shock visible. it seems to absorb shock by shifting forward on 2 pivots on each side of the barrel. one side of the barrel has an allen wrench slot which i assume is for adjustment. i would take it apart & investigate but i'm afraid springs & misc. parts would come exploding out of it like a swiss watch. i know it's not much to go on, but can anybody tell me what type of device this is, what the hell's inside of there, and, especially, whether it needs maintenance or adjustment? Thanks.