We have two types of Ottomans :  Both have a wool/alpaca and silk/tencel accents; type one  has a softer interior (polyfil) and the second type has a firmer interior(polystyrene beads). 

 Any ottoman can be sat on ; the softer interior will flatten more when sat on (much like a soft couch cushion) - this will return to its original shape after a short period of time. The firmer interior will flatten a small amount much like a furniture ottoman and it will return to it’s original shape quickly after use. 

Please make sure to check if the interior fill is the type that you want in the  ottoman that you like.