Name (genus) : Vorticella

Size : The ‘bell’ is up to 150 µm, with stalk up to 1 mm.

Where to find them : Attached to algae and plants etc.

Notes : Vorticella are one of the peritrich protozoa. Although solitary, they often occur in groups to form a tiny jelly-like mass just visible to the naked eye. Their stalks contract like a spring. Some similar types e.g. Epistylis (not contractile) and Carchesium(contractile) are true colonies with branching tree-like stalks.

Classification : 
Kingdom Protoctista, Phylum Ciliophora

more here: http://www.microscopy-uk.org.uk/index-no-ads.html?http://www.microscopy-uk.org.uk/ponddip/vorticella.html