Fire essling

Fire esslings are a type of Essling found on the lower and upper floors of the Runespan (but not the middle floor). They can be siphoned for fire runes, requiring one rune essence and giving one fire rune and 17.4 Runecrafting experience for a successful siphon; an unsuccessful siphon will give no runes, consume no essence, and give 0-2 experience. They require level 14 Runecrafting to siphon. You can absorb 5 fire runes before the essling dies, leaving 50 rune essence. However, if the player stopped siphoning before the essling was drained, they will not receive any essence. They respawn every 5 seconds.

Chipping
Fire esslings can also be "chipped" for rune essence. By using 10 water runes on the essling, you will receive 10-20 rune essence. However, the same fire essling cannot be chipped twice in a row; you can't chip the same creature until you have chipped three other Runespan creatures of any type.

Lower level
Fire esslings can be found on platforms 3, 5, 15, 20, 21, 31, 32, 34, 37, 41, 44, 45, 48, and 49 of the lower floor.

Middle level
Fire esslings are not found on the middle floor.

Upper level
Fire esslings can be found on platforms 7 and 10 of the upper floor.

Trivia

 * Essling is a portmanteau of essence and "ling" meaning either child of, or smaller creature.
 * Fire Esslings have the fire rune symbol on the top of their heads.