Our party was investigating a crypt that led in to some darker tunnels when we came across a room with something quite curious in one of its corners. A five-foot wide pit cut off the corner from the rest of the room, and was wide and deep enough to make getting across a more than trivial task. We wanted to get across the pit because there was something tempting, a chest perhaps, in that corner of the room. Well, it was more hanging in the corner of the room, as it appeared to be suspended a few feet from the ground, motionless. We had no idea what was keeping it suspended above the floor, but we wanted the loot regardless.
The first thing we did was to get closer to the corner to see what mysterious force was holding up the loot, but even then we didn't have the faintest idea what was going on. We started coming up with ideas to get to the loot from the corner. As I was playing an Elven Mage, looking to become an Arcane Archer, one of the ideas I came up with was to send my Raven Familiar, Quoth, across the pit to pick up the loot and bring it back in his talons. This idea wasn't approved as we didn't know the weight of the loot and didn't want it dropped in the pit.
We decided early on that climbing down the pit on this side and back up on the other side just wasn't an option, and we also had nothing physical we could use to bridge the gap. Going out of the crypt and back to the mansion to find a ladder to use as a bridge was not approved, as we didn't want to waste too much time. The idea we finally decided on was for the best jumper in the party to jump the pit, retrieve the loot, and jump back. We tied a rope to him and had other party members hold it so that if there were any problems with him falling in to the pit or getting stuck in what we still thought was probably a magical stasis field we would just use the rope to pull him back. Brilliant! What could go wrong?
Mere moments before the party volunteer was to jump across the pit I called a temporary halt to things, experiencing some sort of pang that we hadn't explored all the options of what was causing the loot to be held in mid-air in the corner of the room. Just to see if it were a force or stasis field, or something else peculiar in effect, I grabbed a handful of dust and grit from the floor of the room and threw it across the pit. To everyone's surprise, as soon as it got across the pit the grit just hung in the air, stationary. This both baffled us and made the volunteer change his mind about jumping across. The party's Fighter was intrigued by the grit just hanging there and got as close as he could to get a better look at just what was occurring here.
And that was the first time we got close enough for a pseudopod of the Gelatinous Cube to be able to lash out at us. Yes, it turned out to be a Gelatinous Cube set-up in the corner of the room as a sort-of trap for unwary adventurers, with the dull light obscuring the Cube from casual detection. The Fighter got a physical smack around the head, and the rest of the party got a virtual slap to wake us all up. A quick bit of ranged fighting later and we were all reflecting on just what would have happened had we followed through on any of our plans without first working out what was in the corner. We could have seen a Familiar or party member 'swallowed' and slowly digested by the Cube. Even then, would we have realised what was going on quickly enough to mount a rescue? Going on the events related here, probably not.
It really is a good thing that we (eventually) looked before we leapt.