Light micrograph of living Gyrosigma sp. diatom (top) and Mayorella sp. amoeba (bottom) out of a Brookside habitat. The Mayorella amoebae feed on microalgae like diatoms. Gyrosigma diatoms have sigmoid frustules and the characteristic brownish chloroplast, the nucleus in the middle of the cell clearly visible. Microscopic contrast technique: Differential interference contrast. Magnification 600x when printed 10 centimetres wide.