Help me and ma car. god bless ya.?

I got uh, amc gremlin, and uh theres this thing under the platform/metal front part of the car. and its uh rattlin. its square and, no its rectangle, shape of uh, a shoebox. its got some yello markins and a big hose comin out of it. im so worried, somebody uh please help. oh yeah and its uh got a big, uh, uh orange bubble stickin out tha side. its got some kind of uh juice in it, its kinda squishy if ya ask me.