1) Buy the tentacle maker kit from Green Stuff Industries
*Edit: and buy some green stuff, get the big tubes not the bullshit that Games Workshop sells
2) Bend two or three thick paperclips into a position you like on the haemo's base, in such a way that they can connect the haemo *to* the base.
3) Once you have your arrangement finalized, use a hand drill to connect the clips to the base and to the haemo. Don't glue in place yet.
4) Make some "tentacles" of various lengths and widths. Wrap or knit some over the paperclips in an arrangement you like. Once you are finalized, glue them in place. Then glue the haemo and the base.
5) Add other smaller "tentacles" to the base as desired.
6) Optionally, sculpt some worm heads.