Sculk Lurker

The deep dark feels empty. Only one native mob, one structure, and a few blocks. With the sculk lurker, it would make the deep dark more interesting. They would be like smaller, thinner wardens, and they would have really long arms that they move around on. They wouldn't spawn naturally, but could spawn whenever you set off a shrieker, except for when you spawn a warden. Alternatively, it could spawn from catalysts. Maybe it would only be partially blind, and it wouldn't cause darkness. Upon death, it could drop and echo shard, and make a loud noise that sets off all sculk sensors in a ten block radius.