Interesting dogwhelk behavior in lab

The other day I was working with dogwhelks in the lab and I noticed one of them was stuck hanging from the top of the cage by a byssal thread. Apparently, a mussel had attached a thread to it and when I turned the cage on its side, the dogwhelk was dangling by it. The poor thing was clearly trying to grab something to get unstuck, but there wasn't much for it to hold onto. I wanted to see if it could get itself out of its unfortunate situation, so I set up my GoPro and started filming!

I soon noticed another dogwhelk crawling up the side of the tank and heading directly toward the top where the dangling dogwhelk was attached. It then proceeded to push on the threads, causing the dangling whelk to bounce! Was this dogwhelk trying to free the dangling one? Here is the 8x speed footage!

I waited a long time for the scene to progress, but the helper dogwhelk didn't break the byssal thread and eventually crawled away. The dangling one wasn't able to grab anything on its own, so I pushed it over to the side of the tank where it held onto the wall, started crawling, and eventually broke the thread and freed itself.