It's a transitioning room, plus the spriteset featuring that ghost is very limited. It carries the player to two other rooms to get keys.
Speaking of which, here's one of those rooms.
Taking some direct cues from Golden Yoshi's work here. The player needs to go across the gap to collect the key and run back as a Chomp Shark chases them. I've added some coins and Baron von Zeppelins to this room since taking these shots.
EDIT 2: Actually, turns out that that the maces combined with the ghost cause horrific lag when Yoshi has a lot of eggs, so I'm ditching them.