The sand-sifting star is very easy to care for. I have one who likes to meander throughout the tank. Sometimes it's buried in the sand, other times it cruises along the sand and sometimes even up the glass.
Tiger Tail Cukes are easy to care for, IF you watch your water parameters and do a very gradual acclimatization. When stressed cukes literally "spill their guts" which can poison the tank. I purchased mine from
Welcome to Pacific East Aquaculture as part of a cleaner pack. I have 3 for my 90 gal and they do a great job. They hide during the day and come out at night.