Come at it from a better angle

code/modules/mob/living/carbon/human/death.dm

@@ -61,10 +61,8 @@
 	animation.master = src
 
 	flick("dust-h", animation)
-	if(!isSynthetic())
-		new /obj/effect/decal/remains/human(loc)
-	else
-		new /obj/effect/decal/cleanable/blood/gibs/robot(loc)
+	new species.remains_type(get_turf(src))
+	if(isSynthetic())
 		var/datum/effect/system/spark_spread/s = new /datum/effect/system/spark_spread
 		s.set_up(3, 1, src)
 		s.start()

code/modules/mob/living/carbon/human/species/species.dm

@@ -90,6 +90,7 @@
 	var/blood_color = "#A10808" //Red.
 	var/flesh_color = "#FFC896" //Pink.
 	var/single_gib_type = /obj/effect/decal/cleanable/blood/gibs
+	var/remains_type = /obj/effect/decal/remains/human //What sort of remains is left behind when the species dusts
 	var/base_color      //Used when setting species.
 
 	//Used in icon caching.

code/modules/mob/living/carbon/human/species/station.dm

@@ -500,6 +500,7 @@
 	deform = 'icons/mob/human_races/r_slime.dmi'
 	path = /mob/living/carbon/human/slime
 	unarmed_type = /datum/unarmed_attack/punch
+	remains_type = /obj/effect/decal/remains/slime
 
 	// More sensitive to the cold
 	cold_level_1 = 280
@@ -730,6 +731,7 @@
 	unarmed_type = /datum/unarmed_attack/diona
 	//primitive_form = "Nymph"
 	slowdown = 5
+	remains_type = /obj/effect/decal/cleanable/ash
 
 	warning_low_pressure = 50
 	hazard_low_pressure = -1
@@ -844,6 +846,7 @@
 	default_language = "Galactic Common"
 	language = "Trinary"
 	unarmed_type = /datum/unarmed_attack/punch
+	remains_type = /obj/effect/decal/remains/robot
 
 	eyes = "blank_eyes"
 	brute_mod = 2.5 // 100% * 2.5 * 0.6 (robolimbs) ~= 150%