Magnum Sea Cucumbers can reach 30 cm (a foot) long but you wouldn’t know it because they live in burrows in soft, sandy sediment in southeast Asia. All you can see of them is a collection of thick, branching, oral tentacles surrounding a cavernous maw.
They hold out those fluffy tentacles to filter tiny crumbs of food from the water and then, once sufficiently laden with detritus, they stuff one of them into their oversized, bucket-like mouth. Now smaller, branched tentacles set to work scraping off the crumbs so they can drop into open gob below.
It’s a nice system, really. And just a little bit mesmerising, too!