The rhomboids, serratus anterior, external obliques, and internal obliques are involved in the serape effect. The muscles that perform this function are the rhomboids and the trapezius. The two rhomboids are sometimes fused into a single muscle. As such, the muscle is an antagonist to the rhomboids. The ornaments include rhomboids, stripes and a green-yellowish reed mat imitation. The side panels are decorated with hatched rhomboids. Some crystals are formed in three-dimensional rhomboids. The hatched rhomboids were also replaced with small ray or tongue patterns. The "major" in its name indicates that it is the larger of the two rhomboids. Rhomboids do not cleave all transmembrane domains. Rhomboids are perhaps the best characterised class. Rhomboids were the first intramembrane proteases for which a high resolution crystal structure was solved. Rhomboids were first discovered as proteases that regulate EGF receptor signalling in "Drosophila".