Cecaeliae are aquatic humanoids which bear a strong resemblance to octopi. They have human-like torsos, which are typically slender; however, even above the waist, there are marked differences between a cecaelia and an elf. They have gills on the sides of their necks, and their eyes are all one solid color.

Below their waists, cecaeliae have powerful tentacles in place of legs. These long, thick limbs are deceptively dexterous, capable of fairly fine motor control, and covered in suckers. Even while stationary, a cecaelia's tentacles are typically in constant motion, independently feeling out the environment around them and stabilizing their body.

Cecaelia skin colors tend to be rather close to human skin tones; however, their tentacles can be any shade of color, from green to purple to red, and their relatively human skin tends to reflect this color to a lesser extent as well. They also have some amount of control over this color and can use it to display some minimal camouflage. They will revert to the same color when not concentrating on blending into their surroundings.