crinoid squat lobsters are not true lobsters like (hawaiian) reef lobsters, and not aggressive IMHO. i have kept several together with Ancylomenes shrimps like pederson cleaner shrimp. they are primarily filter feeders just like anemone crabs but will take the smaller pieces of mysis or brine shrimp floating past them in the water column.
tip: also look for them occasionally on the ‘collector’s corner’ page, not just diver’s den section. they are about $10 less there (but you may not be able to choose the color morph you want).