I'll have to check Island of Terror out.
from IMDB
Island of Terror (1966)
Island of Terror is a great little flick produced by Richard Gordon who also gave us the cult favourite "Fiend Without a Face". Directed with the expertise Hammer director Terence Fisher offers, Gordon has produced a similarly obscure "herd" of creatures to terrorize a high-class cast. The 'Silicates' looks rather silly, like huge turtles with a trunk instead of a head with which they grab their victims, and moves around with the speed of a snail. Like zombies, they are not really a threat when spotted coming, but make up for it with their ability to be anywhere you least expect them. (like up in trees, waiting for passers-by, or underneath cars waiting for someone to enter it). This does get a bit, if not more than a bit, corny, but the ever deadly presence of these creatures, and the nasty way of killing (dissolving the bones, and sucking them out of the body) keeps the fun-bad aspect at bay. There are some great attack sequences at different cast members, and some disgusting slurping when they are "devoured".