pseudopod

valejalka puhekieltä A temporary projection of the cytoplasm of certain cells, such as phagocytes, or of certain unicellular organisms, such as amoebas, that serves in locomotion. (defdate)
puhekieltä A projection acting as a foot in certain insect larvae. (defdate)
By extension, an extension or projection from something. (defdate)
1937, (w), ‘The Salem Horror’:

A pseudopod of blackness elongated itself from the central mass and like a great tentacle clutched the corpse-like being, dragged it back to the pit and over the brink.