Frills are mutations that sprout out around the posterior side of the skull but are not necessarily horns.
A fleshy frill begins anywhere from behind the eyes to the base of the skull and travels down anywhere from midway down the neck to the shoulders. This type of frill can open and close on command and often has bright colours or markings.
A fold of loose skin hanging from the neck or throat of a colonist. Colonists with this can often spread it out for displays. Dewlaps can always have a tone that appears more similar to the blood colour of the species and this can soften into a gradient out into the rest of the base coat.
A fleshy, webbed frill that sprouts out from the posterior side of the skull. It can be moved and either flattened across the neck or spread like a lizard.