My daughter loves super squishy jelly for a messy play time. As it comes in lots of different colours and flavours, and it’s so inexpensive, you can use it for all sorts of different sensory play experiences.
"It senses activity kids. I do a 'feely' activity when learning the 'how we do science,' this idea organizes those 'touchy' things. I would leave the description off because I want my students to use their own words to describe the feel.