assorted dungeon bridges

Roll d12 for your conveyance across.  Mind the gap.

1. Bone bridge formed from spine and ribcage of immense reptile lashed together with magically-preserved sinews.  Worthy example of caveman or barbarian engineering. 
2. Chitin bridge formed of interlocking lacquered giant insect exoskeletons capable of bearing immense weight with barely-perceptible creaking.
3. 'Dancing flagstones' rise between massive levitating menhirs to form a 5' section of bridge per person, moving ahead or behind according to their direction of movement. Loss of consciousness results in the relevant section collapsing after 1d6 rounds to drop hapless delvers. 
4. Glowing blue coals held together by shimmering sheets of force form underlit span.  Edges are very hot, touching them does 1d4 fire damage and ignites flammable materials. Obvious magic is obvious,  worthy example of efreet engineering.
5. 'Invisible' buttressed bridge of thick glass blocks.  Slippery underfoot, edges can be found by spilling sand, dust or opaque liquids.  Those aware of stonecraft or secret doors know where the edges are.
6. Lethal wood and rope bridge with missing boards.  Jumping up and down or combat gives cumulative 10% chance per person that a board will break underfoot with 1 in 6 chance of falling through. 
7. Net of chains forms unsupported bridge.  Walk slowly or crawl swiftly to avoid stumbling. Lose Dexterity bonus to your AC and if you drop something small here, it's 80% likely to be fall through.  
8. Paired ropes allowing man or elf-sized to go hand over hand while walking the lower rope.  Dwarves have to reach up while halflings cling sloth-like or try tightrope walking.  Combat might be risky, kiss goodbye to any Dexterity bonus and try not falling if you get hit.
9. Petrified bodies cemented together so you walk upon stone backs to cross the bridge.  Realistic faces and hands as decorative features. Casting stone to flesh makes the bridge collapse after three rounds in a Grand Guignol.
10. Reinforced stone bridge with tree designs.  Everburning braziers and nightingale flagstones makes moving stealthily across it extremely difficult (half normal chances to do so).
11. Span of woven giant spider silk affixed by magical adhesive,  Springy underfoot yet surprisingly strong. Combat not advised, sharp weapons or fire will destroy the span if 20 points of damage is done to a 5' section. 
12. Zombified colossal worm suspended on dozens of hooked chains, surgically mutilated to form a covered bridge.  More hit points than a small European country, smells vile, guarded by ghouls who snack on it without destroying it.  Cannot be turned by your cleric, though the ghouls can be.