Despite its best efforts, the slime did need another two stalactites to fall before it was big enough to snowball down (or rather up) the food chain. How long did it take for two more stalactites to fall? Well, about as long as it took to actively watch grass grow.
In other words, it didn't know, but it didn't matter either because it was just too damn long. A felt eternity was spent just sitting around. Literally, as the slime had found the perfect hunting strategy. By disguising itself as a piece of tasty, tasty moss it attracted the shield like bugs that consumed it. They thought they were on their way to an easy meal, in truth the slime had spread itself thin in the surrounding area. Once they were close enough to try and eat the moss, and they could eat it since it was a perfect copy, it rolled up from behind them while raising up its main body from underneath the moss.
It was effective, but it was boring, but it was very effective. The only downside was that it had to move every now and again. The slime's prey was just smart enough to realize that this bush of stationary moss was no good after a couple of their kin were lost to it. They were not smart enough to realize that the slightly different shaped moss that appeared elsewhere could not be trusted either. With all of that in mind, and the goal to gain biomass, this was the most meaningful way to spend the time between downing moss.
Now, however, after cleaning off the last bit of scrap moss from the latest deliverance of fate, the slime had reached the size of an average human's palm. That had several advantages, it could now maintain up to four different outgrowths at a time. However, it also discovered a problem. The growths didn't scale. The tail that had allowed it to dash initially was entirely useless at this point. An attempt at the 'just grow multiple ones' had come out as an unnavigable mess.
It didn't have to go back to crawling thanks to using two sets of the six insect legs, moving essentially like a centipede, but its new weight-class wasn't a 100% positive improvement. Rather than moving straight up in power, the slime felt more like it was moving diagonally. Until it ate a creature with better legs, what it improvised had to make due.
Another problem with being bigger was that ambushing was harder than before. Luckily, the slime had already solved that problem with the trapping strategy. On the bright side: It was too big to be considered food by the water dragons anymore, even if it hadn't eaten or even fought one itself yet. Also, the next item on its list of foods did not possess the mobility required to even get out of the way of an ambush.
Clams, that was what the slime was now heading towards. The armoured muscles had no real predators in these waters, so there was a vast bank of them at the east side of the lake. As filter-feeders, all the clams needed to do to eat was exist someplace where they could filter-feed. What controlled their population was a mixture of a parasitic worm that managed to infiltrate the shells of weakened clams and the amount of food that was provided.
In many ways, the slime was the clam's worst nightmare. One would think that, if clams could be afraid of any natural predators, it would the starfish. In that way these clams here had lucked out. There was no star-shaped predator around that could stem open their shells and then bloat its stomach into them, externally digesting them before pulling the resulting protein sludge into its body.
No, these particular clams were spared from that nightmare. They just laid around in their black and beige shells all day, sometimes moving a few centimetres by extending their muscular tongues and dragging themselves over but otherwise doing as clams do.
Enter the slime. Normally, clams were not in the dietary range of slimes. For a start, most clams lived in saltwater, while slimes preferred to live around freshwater sources. Even if clams and slimes did share a biome, the latter usually didn't have the necessary acidity to break down the clam's shell in a satisfactory timeframe. They would try to eat them when they were desperate, but usually die of starvation before getting through.
THIS particular slime, however, was one of the rare occasions of being acidic enough, which the first clam soon found out, as it closed its shell to escape from the sudden viscous liquid enveloping it. They sat still, the bloated form of the slime was unable to hold more than one clam inside it at a time.
The slime was not aware of what exactly was happening. It heavily disliked the initial taste of the clam, to humans it would have been like licking chalk, but it felt that it was dissolving something, so it decided to wait. Time went by and, as the slime was thinking whether or not it should spit out the clam and go back to being pretend-moss, it finally happened.
An explosion of flavour. The shell was finally gone. Not completely, but a thin point allowed the acidic body fluid to rush inside and hasten the process. Much more importantly, it now tasted the protein rich flesh of the actual body.
Clams, decided the slime, were amazing. The whole waiting was finally worth it as it had a huge amount of food to digest. What was more, this tasted sweet and nourishing, completely different from the gunk eating insects. With something like that inside its proverbial belly, it wasn't even mad about having to sit around and wait.
It took, preparing to envelop the next clam in line, a journey of maybe three steps. Being steps of the slime's size. Living in large clusters of partially melded shells, these animals improved their survival chances by reducing their individual risk of getting eaten. They did that by simply displaying a sheer stupendous number of their kind.
For predators, that strategy meant they had a giant buffet sprawled out in front of them. Even better, as the slime was the only organism properly able to hunt (if that word was even appropriate) these clams, this was more like a 100% chance to win in a gamble. Which, technically, wouldn't be a gamble. It would just be winning.
Yes, the slime had just won a minor victory at life.
That first clam's last bit of flesh dissolved and left behind a very happy slime. Immediately it went to analyse what it was able to do now, having figured out that it could visualize the actual parts and what they would do in its nucleus. There were three organs of noteworthiness. One was the gills to filter feed. Then there was the tongue, or foot however one looked at it. Lastly, there was the organ that grew the shell.
The slime had very little interest in filter feeding, although it reckoned that it couldn't hurt to do it on the side. On the contrary, it could see the use in growing multiple tongues to use as feet while the shell seemed the most useful of all of all them.
All around, the clams were a wonderful addition to its toolkit. Particularly the shell would last for a long time since the useful part of it would just keep growing as long as it kept the organ active.
The slime, keeping a set of gills to filter feed and starting its shell production, began the process of flowing around the next clam. Time to keep licking at the chalk again, as many times as it took to get to the tasty insides again, then to repeat that process over and over again until it was big enough to challenge the apex predator of the lake.