How many Nightshade eggs: 2D4+12 = [4, 4]+12 = 20
DC 15 Knowledge (arcana OR the planes) check to know about the acid that protects the eggs and how to dispose of them properly.
If an egg is broken with a melee weapon, the character who breaks the egg takes 2d4 points of acid damage. Anyone within 5 ft. takes half as much damage. A DC 15 Reflex save halves the damage for the breaker and negates the damage to those within 5 ft.
The acid will react with the stone floor to cause noxious fumes to spread out within a 20 ft. radius. These fumes will cause the characters to become sickened unless a successful DC 15 Fortitude save
The PC gain 100 XP for each egg they destroy properly. Moving them out of the ruins first and then destroying them with fire or ranged weapons. If they simply break them with melee weapons, the PCs only get 25 XP for each egg.