This is a transmission electron micrograph of the siphon (or mouth, or ingestion organelle) of Entosiphon sulcatum
. There are three stout rods comprised of microtubules, and four lamellae which seem to assist in pushing food into the body. Each of the microtubules is about 25 nm in diameter. This species eats filamentous bacteria and other moderately large particles, and this presumably requires a stiff ingestion structure.